diff --git a/.natvis b/.natvis
index 3fd140af..4eb7585c 100644
--- a/.natvis
+++ b/.natvis
@@ -42,8 +42,8 @@
         </Expand>
     </Type>
 
-    <Type Name = "sim_netid">
-        <DisplayString>0x{*((u64 *)this + 1), xb}{*(u64 *)this, xb}</DisplayString>
+    <Type Name = "uid">
+        <DisplayString>0x{hi, xb}{lo, xb}</DisplayString>
     </Type>
 
     <Type Name = "String">
diff --git a/src/app.h b/src/app.h
index 14ab5dbe..e85439f6 100644
--- a/src/app.h
+++ b/src/app.h
@@ -9,6 +9,7 @@ struct app_statistics {
     struct atomic_u64 sock_bytes_received;
     struct atomic_u64 memory_committed;
     struct atomic_u64 memory_reserved;
+    struct atomic_u64 num_arenas;
 };
 
 INLINE struct app_statistics *app_statistics(void)
diff --git a/src/arena.c b/src/arena.c
index d0bc2e9c..0919c432 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -43,6 +43,8 @@ struct arena arena_alloc(u64 reserve)
     /* Arena should be 64k aligned */
     ASSERT(((u64)arena.base & 0xFFFF) == 0);
 
+    atomic_u64_inc_eval(&app_statistics()->num_arenas);
+
     return arena;
 }
 
@@ -53,6 +55,7 @@ void arena_release(struct arena *arena)
     __proffree(arena->base);
     atomic_u64_eval_add_i64(&app_statistics()->memory_committed, -((i64)arena->committed));
     atomic_u64_eval_add_i64(&app_statistics()->memory_reserved, -((i64)arena->reserved));
+    atomic_u64_dec_eval(&app_statistics()->num_arenas);
     sys_memory_release(arena->base);
 }
 
diff --git a/src/bitbuff.c b/src/bitbuff.c
index 5693a1c5..97cd5399 100644
--- a/src/bitbuff.c
+++ b/src/bitbuff.c
@@ -20,7 +20,7 @@ enum dbg_magic {
     DBG_MAGIC_IV        = 0x981f,
     DBG_MAGIC_F32       = 0x56F9,
     DBG_MAGIC_F64       = 0x7053,
-    DBG_MAGIC_U128      = 0xA24E,
+    DBG_MAGIC_UID       = 0xA24E,
     DBG_MAGIC_STRING    = 0x7866,
 };
 
@@ -330,11 +330,11 @@ void bw_write_f64(struct bitbuff_writer *bw, f64 value)
     bw_write_ubits(bw, *(u64 *)&value, 64);
 }
 
-void bw_write_u128(struct bitbuff_writer *bw, u128 value)
+void bw_write_uid(struct bitbuff_writer *bw, struct uid value)
 {
-    _dbg_write_magic(bw, DBG_MAGIC_U128, 128);
-    bw_write_ubits(bw, U128_HI(value), 64);
-    bw_write_ubits(bw, U128_LO(value), 64);
+    _dbg_write_magic(bw, DBG_MAGIC_UID, 128);
+    bw_write_ubits(bw, value.hi, 64);
+    bw_write_ubits(bw, value.lo, 64);
 }
 
 void bw_write_string(struct bitbuff_writer *bw, struct string s)
@@ -577,12 +577,12 @@ f64 br_read_f64(struct bitbuff_reader *br)
     return *(f64 *)&ubits;
 }
 
-u128 br_read_u128(struct bitbuff_reader *br)
+struct uid br_read_uid(struct bitbuff_reader *br)
 {
-    _dbg_read_magic(br, DBG_MAGIC_U128, 128);
+    _dbg_read_magic(br, DBG_MAGIC_UID, 128);
     u64 hi = br_read_ubits(br, 64);
     u64 lo = br_read_ubits(br, 64);
-    return U128(hi, lo);
+    return UID(hi, lo);
 }
 
 struct string br_read_string(struct arena *arena, struct bitbuff_reader *br)
diff --git a/src/bitbuff.h b/src/bitbuff.h
index ea76e0a2..85bff67a 100644
--- a/src/bitbuff.h
+++ b/src/bitbuff.h
@@ -57,7 +57,7 @@ void bw_write_iv(struct bitbuff_writer *bw, i64 value);
 
 void bw_write_f32(struct bitbuff_writer *bw, f32 value);
 void bw_write_f64(struct bitbuff_writer *bw, f64 value);
-void bw_write_u128(struct bitbuff_writer *bw, u128 value);
+void bw_write_uid(struct bitbuff_writer *bw, struct uid value);
 
 void bw_write_string(struct bitbuff_writer *bw, struct string s);
 
@@ -99,7 +99,7 @@ i64 br_read_iv(struct bitbuff_reader *br);
 
 f32 br_read_f32(struct bitbuff_reader *br);
 f64 br_read_f64(struct bitbuff_reader *br);
-u128 br_read_u128(struct bitbuff_reader *br);
+struct uid br_read_uid(struct bitbuff_reader *br);
 
 struct string br_read_string(struct arena *arena, struct bitbuff_reader *br);
 
diff --git a/src/common.h b/src/common.h
index b66eb0a8..8d6952f6 100644
--- a/src/common.h
+++ b/src/common.h
@@ -391,14 +391,14 @@ INLINE u128 u128_mul(u128 a, u128 b) { return a * b; }
 #elif COMPILER_MSVC
 
 #if LANGUAGE_CPP
-# define U128(hi64, lo64) { (hi64), (lo64) }
+# define U128(hi64, lo64) { .hi = (hi64), .lo = (lo64) }
 #else
 # define U128(hi64, lo64) ((u128) { .hi = (hi64), .lo = (lo64) })
 #endif
 #define U128_HI(a) ((a).hi)
 #define U128_LO(a) ((a).lo)
 
-typedef struct { u64 hi; u64 lo; } u128;
+typedef struct { u64 lo; u64 hi; } u128;
 
 INLINE b32 u128_eq(u128 a, u128 b) { return a.hi == b.hi && a.lo == b.lo; }
 INLINE b32 u128_lt(u128 a, u128 b) { return ((((a.hi > b.hi) - (a.hi < b.hi)) << 1) + ((a.lo > b.lo) - (a.lo < b.lo))) < 0; }
@@ -407,6 +407,8 @@ INLINE u128 u128_xor_u8(u128 a, u8 b) { return U128(a.hi, a.lo ^ b); }
 
 /* https://www.codeproject.com/Tips/784635/UInt-Bit-Operations */
 
+/* TODO: Use msvc intrinsics & ensure results are identical to clang */
+
 INLINE u128 u128_mul(u128 a, u128 b)
 {
     u64 a1 = (a.lo & 0xffffffff);
@@ -485,6 +487,19 @@ struct string32 {
     u32 *text;
 };
 
+#define UID(hi, lo) (struct uid) { .v = U128((hi), (lo)) }
+#define UID0 (struct uid) { 0 }
+struct uid {
+    union {
+        u128 v;
+        struct {
+            u64 lo;
+            u64 hi;
+        };
+    };
+};
+INLINE b32 uid_eq(struct uid a, struct uid b) { return u128_eq(a.v, b.v); }
+
 struct image_rgba {
     u32 width;
     u32 height;
@@ -501,10 +516,6 @@ struct sim_ent_handle {
     u64 gen;
 };
 
-struct sim_netid {
-    u128 v;
-};
-
 struct sim_client_handle {
     u32 idx;
     u32 gen;
diff --git a/src/rng.c b/src/rng.c
index 0fcce607..e9f52ed5 100644
--- a/src/rng.c
+++ b/src/rng.c
@@ -78,6 +78,13 @@ u128 rng_rand_u128(void)
     return v;
 }
 
+struct uid rng_rand_uid(void)
+{
+    u128 v = 0;
+    sys_rand(STRING_FROM_STRUCT(&v));
+    return (struct uid) { .v = v };
+}
+
 f32 rng_rand_f32(f32 range_start, f32 range_end)
 {
     return ((f32)rng_rand_u32() / (f32)U32_MAX) * (range_end - range_start) + range_start;
diff --git a/src/rng.h b/src/rng.h
index 6bfc84f0..20d2922b 100644
--- a/src/rng.h
+++ b/src/rng.h
@@ -11,6 +11,7 @@ struct rng_startup_receipt rng_startup(struct resource_startup_receipt *resource
 u32 rng_rand_u32(void);
 u64 rng_rand_u64(void);
 u128 rng_rand_u128(void);
+struct uid rng_rand_uid(void);
 f32 rng_rand_f32(f32 range_start, f32 range_end);
 f64 rng_rand_f64(f64 range_start, f64 range_end);
 
diff --git a/src/sim.c b/src/sim.c
index 74ba8b58..80c37769 100644
--- a/src/sim.c
+++ b/src/sim.c
@@ -25,7 +25,7 @@
 
 #define CLIENT_LOOKUP_BUCKETS 127
 #define TICK_LOOKUP_BUCKETS 127
-#define NETID_LOOKUP_BUCKETS 1024
+#define UID_LOOKUP_BUCKETS 4096
 
 /* ========================== *
  * Startup
@@ -305,18 +305,18 @@ struct sim_snapshot *sim_snapshot_alloc(struct sim_client *client, struct sim_sn
     ss->sim_dt_ns = src->sim_dt_ns;
     ss->sim_time_ns = src->sim_time_ns;
     ss->continuity_gen = src->continuity_gen;
-    ss->local_client_netid = src->local_client_netid;
+    ss->local_client_ent_uid = src->local_client_ent_uid;
     ss->phys_iteration = src->phys_iteration;
 
-    /* Copy netid lookup buckets */
-    ss->num_netid_buckets = src->num_netid_buckets > 0 ? src->num_netid_buckets : NETID_LOOKUP_BUCKETS;
-    ss->netid_buckets = arena_push_array(&ss->arena, struct sim_ent_bucket, ss->num_netid_buckets);
-    if (src->num_netid_buckets > 0) {
-        for (u64 i = 0; i < src->num_netid_buckets; ++i) {
-            ss->netid_buckets[i] = src->netid_buckets[i];
+    /* Copy uid lookup buckets */
+    ss->num_uid_buckets = src->num_uid_buckets > 0 ? src->num_uid_buckets : UID_LOOKUP_BUCKETS;
+    ss->uid_buckets = arena_push_array(&ss->arena, struct sim_ent_bucket, ss->num_uid_buckets);
+    if (src->num_uid_buckets > 0) {
+        for (u64 i = 0; i < src->num_uid_buckets; ++i) {
+            ss->uid_buckets[i] = src->uid_buckets[i];
         }
     } else {
-        MEMZERO(ss->netid_buckets, sizeof(*ss->netid_buckets) * ss->num_netid_buckets);
+        MEMZERO(ss->uid_buckets, sizeof(*ss->uid_buckets) * ss->num_uid_buckets);
     }
 
     /* Copy entities */
@@ -586,7 +586,7 @@ void sim_snapshot_encode(struct bitbuff_writer *bw, struct sim_client *receiver,
     bw_write_uv(bw, ss1->continuity_gen);
     bw_write_uv(bw, ss1->phys_iteration);
 
-    bw_write_u128(bw, receiver->client_ent_netid.v);
+    bw_write_uid(bw, receiver->ent_uid);
 
     /* Ents */
     if (ss1->num_ents_allocated == ss0->num_ents_allocated) {
@@ -625,7 +625,7 @@ void sim_snapshot_decode(struct bitbuff_reader *br, struct sim_snapshot *ss)
     ss->continuity_gen = br_read_uv(br);
     ss->phys_iteration = br_read_uv(br);
 
-    ss->local_client_netid.v = br_read_u128(br);
+    ss->local_client_ent_uid = br_read_uid(br);
 
     /* Ents */
     if (br_read_bit(br)) {
diff --git a/src/sim.h b/src/sim.h
index 6b4796ab..858cb1f7 100644
--- a/src/sim.h
+++ b/src/sim.h
@@ -79,8 +79,8 @@ struct sim_client {
     struct sim_client_handle next_in_bucket;
     struct sim_client_handle prev_in_bucket;
 
-    /* The client entity's net id in the master sim (if relevant) */
-    struct sim_netid client_ent_netid;
+    /* The client entity's uid in the master sim (if relevant) */
+    struct uid ent_uid;
 
     /* This is the highest confirmed tick of ours that we know this client has received */
     u64 ack;
@@ -171,11 +171,11 @@ struct sim_snapshot {
     /* The last physics iteration (used for tracking contact lifetime) */
     u64 phys_iteration;
 
-    struct sim_netid local_client_netid;  /* The netid of the receiver's client ent */
+    struct uid local_client_ent_uid;  /* The uid of the receiver's client ent */
 
-    /* Net id lookup */
-    struct sim_ent_bucket *netid_buckets;
-    u64 num_netid_buckets;
+    /* Uid lookup */
+    struct sim_ent_bucket *uid_buckets;
+    u64 num_uid_buckets;
 
     /* Entities */
     struct arena ents_arena;
@@ -211,15 +211,11 @@ struct sim_snapshot *sim_snapshot_alloc_from_lerp(struct sim_client *client, str
 void sim_snapshot_encode(struct bitbuff_writer *bw, struct sim_client *receiver, struct sim_snapshot *ss0, struct sim_snapshot *ss1);
 void sim_snapshot_decode(struct bitbuff_reader *br, struct sim_snapshot *ss);
 
-/* ========================== *
- * Net id
- * ========================== */
 
-#define SIM_NETID_NIL (struct sim_netid) { U128(0, 0) }
 
-INLINE b32 sim_netid_eq(struct sim_netid a, struct sim_netid b)
-{
-    return u128_eq(a.v, b.v);
-}
+
+
+
+
 
 #endif
diff --git a/src/sim_ent.c b/src/sim_ent.c
index b32d5900..1038dcd6 100644
--- a/src/sim_ent.c
+++ b/src/sim_ent.c
@@ -39,35 +39,38 @@ struct sim_ent *sim_ent_alloc_local(struct sim_ent *parent)
     struct sim_snapshot *ss = parent->ss;
     struct sim_ent *e = sim_ent_alloc_raw(ss);
     sim_ent_link_parent(e, parent);
+
+    sim_ent_set_uid(e, rng_rand_uid());
+
     return e;
 }
 
-/* Allocates a new entity with a random netid to be synced to clients */
+/* Allocates a new entity with a random uid to be synced to clients */
 struct sim_ent *sim_ent_alloc_net_src(struct sim_ent *parent)
 {
     struct sim_snapshot *ss = parent->ss;
     struct sim_ent *e = sim_ent_alloc_raw(ss);
     sim_ent_link_parent(e, parent);
 
+    sim_ent_set_uid(e, rng_rand_uid());
+
     sim_ent_enable_prop(e, SIM_ENT_PROP_NET_SRC);
-    struct sim_netid netid = ZI;
-    netid.v = rng_rand_u128();
     e->net_src_client = ss->client->handle;
-    sim_ent_set_netid(e, netid);
 
     return e;
 }
 
-/* Allocates a new entity that will sync with incoming net src ents containing netid, and coming from the specified client */
-struct sim_ent *sim_ent_alloc_net_dst(struct sim_ent *parent, struct sim_client_handle client_handle, struct sim_netid netid)
+/* Allocates a new entity that will sync with incoming net src ents containing uid, and coming from the specified client */
+struct sim_ent *sim_ent_alloc_net_dst(struct sim_ent *parent, struct sim_client_handle client_handle, struct uid uid)
 {
     struct sim_snapshot *ss = parent->ss;
     struct sim_ent *e = sim_ent_alloc_raw(ss);
     sim_ent_link_parent(e, parent);
 
+    sim_ent_set_uid(e, uid);
+
     sim_ent_enable_prop(e, SIM_ENT_PROP_NET_DST);
     e->net_src_client = client_handle;
-    sim_ent_set_netid(e, netid);
 
     return e;
 }
@@ -83,8 +86,8 @@ void sim_ent_release_raw(struct sim_ent *ent)
         }
     }
 
-    /* Release netid */
-    sim_ent_set_netid(ent, SIM_NETID_NIL);
+    /* Release uid */
+    sim_ent_set_uid(ent, UID0);
 
     /* Release */
     ++ent->handle.gen;
@@ -103,38 +106,38 @@ void sim_ent_release(struct sim_ent *ent)
 }
 
 /* ========================== *
- * Net id
+ * Uid
  * ========================== */
 
-INLINE u64 hash_from_netid(struct sim_netid netid)
+INLINE u64 hash_from_uid(struct uid uid)
 {
-    /* Just use lower 64 bits of netid since it's already randomnized */
-    return U128_LO(netid.v);
+    /* Just use lower 64 bits of uid since it's already randomnized */
+    return uid.lo;
 }
 
-struct sim_netid sim_ent_get_netid(struct sim_ent *ent)
+struct uid sim_ent_get_uid(struct sim_ent *ent)
 {
-    return ent->_netid;
+    return ent->_uid;
 }
 
-void sim_ent_set_netid(struct sim_ent *ent, struct sim_netid netid)
+void sim_ent_set_uid(struct sim_ent *ent, struct uid uid)
 {
     struct sim_snapshot *ss = ent->ss;
-    struct sim_ent_bucket *buckets = ss->netid_buckets;
-    u64 num_netid_buckets = ss->num_netid_buckets;
+    struct sim_ent_bucket *buckets = ss->uid_buckets;
+    u64 num_uid_buckets = ss->num_uid_buckets;
 
-    struct sim_netid old_netid = ent->_netid;
+    struct uid old_uid = ent->_uid;
 
     /* Release old from lookup */
-    if (!sim_netid_eq(old_netid, SIM_NETID_NIL)) {
-        u64 hash = hash_from_netid(old_netid);
-        struct sim_ent_bucket *bucket = &buckets[hash % num_netid_buckets];
+    if (!uid_eq(old_uid, UID0)) {
+        u64 hash = hash_from_uid(old_uid);
+        struct sim_ent_bucket *bucket = &buckets[hash % num_uid_buckets];
         struct sim_ent *prev = sim_ent_nil();
         struct sim_ent *next = sim_ent_nil();
         struct sim_ent *e = sim_ent_from_handle(ss, bucket->first);
         while (e->valid) {
-            next = sim_ent_from_handle(ss, e->next_in_netid_bucket);
-            if (sim_netid_eq(e->_netid, old_netid)) {
+            next = sim_ent_from_handle(ss, e->next_in_uid_bucket);
+            if (uid_eq(e->_uid, old_uid)) {
                 break;
             }
             prev = e;
@@ -142,44 +145,44 @@ void sim_ent_set_netid(struct sim_ent *ent, struct sim_netid netid)
         }
         if (e->valid) {
             if (prev->valid) {
-                prev->next_in_netid_bucket = next->handle;
+                prev->next_in_uid_bucket = next->handle;
             } else {
                 bucket->first = next->handle;
             }
             if (next->valid) {
-                next->prev_in_netid_bucket = prev->handle;
+                next->prev_in_uid_bucket = prev->handle;
             } else {
                 bucket->last = prev->handle;
             }
         }
     }
 
-    /* Insert new netid into lookup */
-    if (!sim_netid_eq(netid, SIM_NETID_NIL)) {
-        u64 hash = hash_from_netid(netid);
-        struct sim_ent_bucket *bucket = &buckets[hash % num_netid_buckets];
+    /* Insert new uid into lookup */
+    if (!uid_eq(uid, UID0)) {
+        u64 hash = hash_from_uid(uid);
+        struct sim_ent_bucket *bucket = &buckets[hash % num_uid_buckets];
         struct sim_ent *last = sim_ent_from_handle(ss, bucket->last);
         if (last->valid) {
-            last->next_in_netid_bucket = ent->handle;
+            last->next_in_uid_bucket = ent->handle;
         } else {
             bucket->first = ent->handle;
         }
-        ent->prev_in_netid_bucket = last->handle;
+        ent->prev_in_uid_bucket = last->handle;
         bucket->last = ent->handle;
     }
 
-    ent->_netid = netid;
+    ent->_uid = uid;
 }
 
-struct sim_ent *sim_ent_from_netid(struct sim_snapshot *ss, struct sim_netid netid)
+struct sim_ent *sim_ent_from_uid(struct sim_snapshot *ss, struct uid uid)
 {
     struct sim_ent *res = sim_ent_nil();
-    u64 num_buckets = ss->num_netid_buckets;
-    if (num_buckets > 0 && !sim_netid_eq(netid, SIM_NETID_NIL)) {
-        u64 hash = hash_from_netid(netid);
-        struct sim_ent_bucket *bucket = &ss->netid_buckets[hash % num_buckets];
-        for (struct sim_ent *e = sim_ent_from_handle(ss, bucket->first); e->valid; e = sim_ent_from_handle(ss, e->next_in_netid_bucket)) {
-            if (sim_netid_eq(e->_netid, netid)) {
+    u64 num_buckets = ss->num_uid_buckets;
+    if (num_buckets > 0 && !uid_eq(uid, UID0)) {
+        u64 hash = hash_from_uid(uid);
+        struct sim_ent_bucket *bucket = &ss->uid_buckets[hash % num_buckets];
+        for (struct sim_ent *e = sim_ent_from_handle(ss, bucket->first); e->valid; e = sim_ent_from_handle(ss, e->next_in_uid_bucket)) {
+            if (uid_eq(e->_uid, uid)) {
                 res = e;
                 break;
             }
@@ -496,7 +499,7 @@ void sim_ent_encode(struct bitbuff_writer *bw, struct sim_ent *e0, struct sim_en
 
 
     /* FIXME: Things like xforms need to be retreived manually rather than memcopied.
-     *  This will also be true for things like ent handles once netids are implemented. */
+     *  This will also be true for things like ent handles once uids are implemented. */
 
     /* TODO: Granular delta encoding */
 
@@ -527,7 +530,7 @@ void sim_ent_decode(struct bitbuff_reader *br, struct sim_ent *e)
 {
     struct sim_snapshot *ss = e->ss;
 
-    struct sim_netid old_netid = sim_ent_get_netid(e);
+    struct uid old_uid = sim_ent_get_uid(e);
 
     u64 pos = 0;
     while (pos < sizeof(*e)) {
@@ -540,10 +543,10 @@ void sim_ent_decode(struct bitbuff_reader *br, struct sim_ent *e)
         pos += 8;
     }
 
-    struct sim_netid new_netid = sim_ent_get_netid(e);
-    e->_netid = old_netid;
-    if (!sim_netid_eq(old_netid, new_netid)) {
-        sim_ent_set_netid(e, new_netid);
+    struct uid new_uid = sim_ent_get_uid(e);
+    e->_uid = old_uid;
+    if (!uid_eq(old_uid, new_uid)) {
+        sim_ent_set_uid(e, new_uid);
     }
 
     e->ss = ss;
diff --git a/src/sim_ent.h b/src/sim_ent.h
index 57ab85cc..11c15bb3 100644
--- a/src/sim_ent.h
+++ b/src/sim_ent.h
@@ -62,10 +62,17 @@ struct sim_ent {
     /* ====================================================================== */
     /* Metadata */
 
-    b32 valid;  /* Is this ent allocated in memory that can be written to (can always be read) */
-    struct sim_ent_handle handle;
     struct sim_snapshot *ss;
 
+    b32 valid;  /* Is this ent allocated in memory that can be written to (can always be read) */
+
+    struct sim_ent_handle handle;
+
+    /* The unique ID of the entity determined at allocation time.
+     * Mainly used for networking.
+     * Use uid getter to access. */
+    struct uid _uid;
+
     u64 props[(SIM_ENT_PROP_COUNT + 63) / 64];
     u64 continuity_gen;
 
@@ -85,8 +92,8 @@ struct sim_ent {
     struct sim_ent_handle first;
     struct sim_ent_handle last;
 
-    struct sim_ent_handle next_in_netid_bucket;
-    struct sim_ent_handle prev_in_netid_bucket;
+    struct sim_ent_handle next_in_uid_bucket;
+    struct sim_ent_handle prev_in_uid_bucket;
 
     struct sim_ent_handle next_free;
 
@@ -99,10 +106,6 @@ struct sim_ent {
     /* Handle of the client that owns the src ent of this dst ent */
     struct sim_client_handle net_src_client;
 
-    /* The (unique) networked ID of the entity.
-     * Use net getter to access. */
-    struct sim_netid _netid;
-
     /* ====================================================================== */
     /* Position */
 
@@ -132,7 +135,7 @@ struct sim_ent {
 
     struct sim_ent_handle cmd_client;
     struct sim_control cmd_control;
-    struct sim_netid cmd_hovered_ent_netid;
+    struct uid cmd_hovered_ent_uid;
 
     /* ====================================================================== */
     /* Client */
@@ -396,16 +399,16 @@ INLINE b32 sim_ent_is_valid_and_active(struct sim_ent *ent)
 struct sim_ent *sim_ent_alloc_raw(struct sim_snapshot *ss);
 struct sim_ent *sim_ent_alloc_local(struct sim_ent *parent);
 struct sim_ent *sim_ent_alloc_net_src(struct sim_ent *parent);
-struct sim_ent *sim_ent_alloc_net_dst(struct sim_ent *parent, struct sim_client_handle client_handle, struct sim_netid netid);
+struct sim_ent *sim_ent_alloc_net_dst(struct sim_ent *parent, struct sim_client_handle client_handle, struct uid uid);
 
 void sim_ent_release_raw(struct sim_ent *ent);
 void sim_ent_release(struct sim_ent *ent);
 
-/* Net id */
+/* Uid */
 
-struct sim_netid sim_ent_get_netid(struct sim_ent *ent);
-void sim_ent_set_netid(struct sim_ent *ent, struct sim_netid netid);
-struct sim_ent *sim_ent_from_netid(struct sim_snapshot *ss, struct sim_netid netid);
+struct uid sim_ent_get_uid(struct sim_ent *ent);
+void sim_ent_set_uid(struct sim_ent *ent, struct uid uid);
+struct sim_ent *sim_ent_from_uid(struct sim_snapshot *ss, struct uid uid);
 
 /* Query */
 struct sim_ent *sim_ent_from_handle(struct sim_snapshot *ss, struct sim_ent_handle handle);
diff --git a/src/sim_step.c b/src/sim_step.c
index 71a1b915..2657e1a4 100644
--- a/src/sim_step.c
+++ b/src/sim_step.c
@@ -168,8 +168,9 @@ void sim_accel_rebuild(struct sim_snapshot *ss, struct sim_accel *accel)
     /* Reset ent space handles */
     for (u64 sim_ent_index = 0; sim_ent_index < ss->num_ents_reserved; ++sim_ent_index) {
         struct sim_ent *ent = &ss->ents[sim_ent_index];
-        if (!sim_ent_is_valid_and_active(ent)) continue;
-        MEMZERO_STRUCT(&ent->space_handle);
+        if (ent->valid) {
+            MEMZERO_STRUCT(&ent->space_handle);
+        }
     }
 
     /* NOTE: Not rebuilding space since it'll happen during phys step */
@@ -177,10 +178,11 @@ void sim_accel_rebuild(struct sim_snapshot *ss, struct sim_accel *accel)
     /* Rebuild lookup tables */
     for (u64 sim_ent_index = 0; sim_ent_index < ss->num_ents_reserved; ++sim_ent_index) {
         struct sim_ent *ent = &ss->ents[sim_ent_index];
-        if (!sim_ent_is_valid_and_active(ent)) continue;
-        if (sim_ent_has_prop(ent, SIM_ENT_PROP_CONTACT_CONSTRAINT)) {
-            struct sim_lookup_key contact_lookup_key = sim_lookup_key_from_two_handles(ent->contact_constraint_data.e0, ent->contact_constraint_data.e1);
-            sim_lookup_set(&accel->contact_lookup, contact_lookup_key, ent->handle);
+        if (sim_ent_is_valid_and_active(ent)) {
+            if (sim_ent_has_prop(ent, SIM_ENT_PROP_CONTACT_CONSTRAINT)) {
+                struct sim_lookup_key contact_lookup_key = sim_lookup_key_from_two_handles(ent->contact_constraint_data.e0, ent->contact_constraint_data.e1);
+                sim_lookup_set(&accel->contact_lookup, contact_lookup_key, ent->handle);
+            }
         }
     }
 }
@@ -667,7 +669,7 @@ void sim_step(struct sim_step_ctx *ctx)
                         }
 
                         /* Dereference hovered ent */
-                        client_ent->client_hovered_ent = sim_ent_from_netid(world, cmd_ent->cmd_hovered_ent_netid)->handle;
+                        client_ent->client_hovered_ent = sim_ent_from_uid(world, cmd_ent->cmd_hovered_ent_uid)->handle;
 
                         u32 flags = control->flags;
                         if (flags & SIM_CONTROL_FLAG_DRAG) {
diff --git a/src/string.c b/src/string.c
index 585b1880..a0ac41be 100644
--- a/src/string.c
+++ b/src/string.c
@@ -463,15 +463,15 @@ struct string string_formatv(struct arena *arena, struct string fmt, va_list arg
                 } break;
 
                 case FMT_TYPE_UINT: {
-                    parsed_str = string_from_uint(arena, arg.value.uint, 10, 0);
+                    parsed_str = string_from_uint(arena, arg.value.uint, 10, arg.zfill);
                 } break;
 
                 case FMT_TYPE_SINT: {
-                    parsed_str = string_from_int(arena, arg.value.sint, 10, 0);
+                    parsed_str = string_from_int(arena, arg.value.sint, 10, arg.zfill);
                 } break;
 
                 case FMT_TYPE_HEX: {
-                    parsed_str = string_from_uint(arena, arg.value.sint, 16, 0);
+                    parsed_str = string_from_uint(arena, arg.value.sint, 16, arg.zfill);
                 } break;
 
                 case FMT_TYPE_PTR: {
@@ -479,7 +479,7 @@ struct string string_formatv(struct arena *arena, struct string fmt, va_list arg
                 } break;
 
                 case FMT_TYPE_FLOAT: {
-                    parsed_str = string_from_float(arena, arg.value.f.val, arg.value.f.precision);
+                    parsed_str = string_from_float(arena, arg.value.f, arg.precision);
                 } break;
 
                 case FMT_TYPE_HANDLE: {
diff --git a/src/string.h b/src/string.h
index b7d07646..fea5c357 100644
--- a/src/string.h
+++ b/src/string.h
@@ -58,16 +58,15 @@ enum fmt_type {
 
 struct fmt_arg {
     enum fmt_type type;
+    u32 precision;
+    u32 zfill;
     union {
         u8 c;
         struct string string;
         u64 uint;
         i64 sint;
         void *ptr;
-        struct {
-            f64 val;
-            u32 precision;
-        } f;
+        f64 f;
         struct {
             u64 h64[2];
         } handle;
@@ -79,11 +78,12 @@ struct fmt_arg {
 #define FMT_CHAR(v) (struct fmt_arg) {.type = FMT_TYPE_CHAR, .value.c = (v)}
 #define FMT_STR(v) (struct fmt_arg) {.type = FMT_TYPE_STR, .value.string = (v)}
 #define FMT_UINT(v) (struct fmt_arg) {.type = FMT_TYPE_UINT, .value.uint = (v)}
+#define FMT_UINT_Z(v, z) (struct fmt_arg) {.type = FMT_TYPE_UINT, .value.uint = (v), .zfill = (z)}
 #define FMT_SINT(v) (struct fmt_arg) {.type = FMT_TYPE_SINT, .value.sint = (v)}
 #define FMT_HEX(v) (struct fmt_arg) {.type = FMT_TYPE_HEX, .value.uint = (v)}
 #define FMT_PTR(v) (struct fmt_arg) {.type = FMT_TYPE_PTR, .value.ptr = (v)}
 #define FMT_FLOAT(v) FMT_FLOAT_P(v, DEFAULT_FMT_PRECISION)
-#define FMT_FLOAT_P(v, p) (struct fmt_arg) {.type = FMT_TYPE_FLOAT, .value.f.val = (v), .value.f.precision = p}
+#define FMT_FLOAT_P(v, p) (struct fmt_arg) {.type = FMT_TYPE_FLOAT, .value.f = (v), .precision = (p)}
 #define FMT_HANDLE(v) (struct fmt_arg) {.type = FMT_TYPE_HANDLE, .value.handle.h64[0] = (v).idx, .value.handle.h64[1] = (v).gen}
 
 #define string_format(arena, fmt, ...) _string_format((arena), (fmt), __VA_ARGS__, FMT_END)
diff --git a/src/user.c b/src/user.c
index d141f9e0..c0b7a8af 100644
--- a/src/user.c
+++ b/src/user.c
@@ -86,7 +86,7 @@ GLOBAL struct {
     /* User -> local sim */
     struct sys_mutex user_sim_cmd_mutex;
     struct sim_control user_sim_cmd_control;
-    struct sim_netid user_sim_cmd_hovered_ent_netid;
+    struct uid user_sim_cmd_hovered_ent_uid;
     u64 last_user_sim_cmd_gen;
     u64 user_sim_cmd_gen;
 
@@ -348,16 +348,17 @@ INTERNAL struct string get_ent_debug_text(struct arena *arena, struct sim_ent *e
     struct string res = ZI;
     res.text = arena_dry_push(arena, u8);
 
+    res.len += string_format(arena, LIT("<%F>"), FMT_HANDLE(ent->handle)).len;
+
+    /* TODO: String fmt function */
+    struct uid uid = sim_ent_get_uid(ent);
+    res.len += string_copy(arena, LIT(" [")).len;
+    res.len += string_from_uint(arena, (U128_HI(uid.v) >> 36) & 0xFFFFFFF, 16, 7).len;
+    res.len += string_copy(arena, LIT("]\n")).len;
+
     {
         res.len += string_copy(arena, LIT("net:          ")).len;
 
-        struct sim_netid netid = sim_ent_get_netid(ent);
-        if (!sim_netid_eq(netid, SIM_NETID_NIL)) {
-            res.len += string_copy(arena, LIT(" [")).len;
-            res.len += string_from_uint(arena, (U128_HI(netid.v) >> 36) & 0xFFFFFFF, 16, 7).len;
-            res.len += string_copy(arena, LIT("]")).len;
-        }
-
         b32 transmitting = sim_ent_has_prop(ent, SIM_ENT_PROP_NET_SRC);
         b32 receiving = sim_ent_has_prop(ent, SIM_ENT_PROP_NET_DST);
         if (transmitting & receiving) {
@@ -405,7 +406,7 @@ INTERNAL struct string get_ent_debug_text(struct arena *arena, struct sim_ent *e
             res.len += string_format(arena, LIT("last child:    <%F>\n"), FMT_HANDLE(ent->last)).len;
         }
         while (child->valid) {
-            res.len += string_format(arena, LIT("\nCHILD <%F>\n"), FMT_HANDLE(child->handle)).len;
+            res.len += string_copy(arena, LIT("\nCHILD\n")).len;
             struct string child_text = get_ent_debug_text(scratch.arena, child);
             res.len += string_indent(arena, child_text, 4).len;
             child = sim_ent_from_handle(ss, child->next);
@@ -698,7 +699,7 @@ INTERNAL void user_update(void)
      * Find local entities
      * ========================== */
 
-    struct sim_ent *local_client_ent = sim_ent_from_netid(G.ss_blended, G.ss_blended->local_client_netid);
+    struct sim_ent *local_client_ent = sim_ent_from_uid(G.ss_blended, G.ss_blended->local_client_ent_uid);
     struct sim_ent *local_player = sim_ent_from_handle(G.ss_blended, local_client_ent->client_control_ent);
     struct sim_ent *local_camera = sim_ent_from_handle(G.ss_blended, local_client_ent->client_camera_ent);
 
@@ -1530,7 +1531,7 @@ INTERNAL void user_update(void)
                 u32 old_flags = G.user_sim_cmd_control.flags;
                 G.user_sim_cmd_control = control;
                 G.user_sim_cmd_control.flags |= old_flags;
-                G.user_sim_cmd_hovered_ent_netid = sim_ent_get_netid(hovered_ent);
+                G.user_sim_cmd_hovered_ent_uid = sim_ent_get_uid(hovered_ent);
                 sys_mutex_unlock(&lock);
             }
         }
@@ -1575,7 +1576,6 @@ INTERNAL void user_update(void)
 
             struct string dbg_text = ZI;
             dbg_text.text = arena_dry_push(temp.arena, u8);
-            dbg_text.len += string_format(temp.arena, LIT("ENT <%F>\n"), FMT_HANDLE(ent->handle)).len;
             dbg_text.len += get_ent_debug_text(temp.arena, ent).len;
             draw_text(G.ui_cmd_buffer, font, pos, dbg_text);
 
@@ -1640,6 +1640,9 @@ INTERNAL void user_update(void)
 
             draw_text(G.ui_cmd_buffer, font, pos, string_format(temp.arena, LIT("Virtual memory usage:  %F TiB"), FMT_FLOAT_P((f64)atomic_u64_eval(&app_statistics()->memory_reserved) / 1024 / 1024 / 1024 / 1024, 3)));
             pos.y += spacing;
+
+            draw_text(G.ui_cmd_buffer, font, pos, string_format(temp.arena, LIT("Arenas allocated:      %F"), FMT_UINT(atomic_u64_eval(&app_statistics()->num_arenas))));
+            pos.y += spacing;
             pos.y += spacing;
 
 #if 0
@@ -1841,8 +1844,8 @@ INTERNAL struct sim_ent_handle _translate(struct sim_snapshot *local_ss, struct
     struct sim_ent_handle local_handle = SIM_ENT_NIL_HANDLE;
     struct sim_ent *remote_ent = sim_ent_from_handle(remote_ss, remote_ent_handle);
     if (remote_ent->valid) {
-        struct sim_netid netid = sim_ent_get_netid(remote_ent);
-        struct sim_ent *local_ent = sim_ent_from_netid(local_ss, netid);
+        struct uid uid = sim_ent_get_uid(remote_ent);
+        struct sim_ent *local_ent = sim_ent_from_uid(local_ss, uid);
         local_handle = local_ent->handle;
     }
     return local_handle;
@@ -1864,15 +1867,15 @@ INTERNAL void sim_ent_sync_remote(struct sim_ent *local, struct sim_ent *remote)
     local->ss = old.ss;
     local->handle = old.handle;
     local->net_src_client = remote_client_handle;
-    local->_netid = old._netid;
+    local->_uid = old._uid;
     local->parent = old.parent;
     local->prev = old.prev;
     local->next = old.next;
     local->first = old.first;
     local->last = old.last;
     local->top = old.top;
-    local->next_in_netid_bucket = old.next_in_netid_bucket;
-    local->prev_in_netid_bucket = old.prev_in_netid_bucket;
+    local->next_in_uid_bucket = old.next_in_uid_bucket;
+    local->prev_in_uid_bucket = old.prev_in_uid_bucket;
     local->next_free = old.next_free;
 
     /* Translate remote handles */
@@ -1891,6 +1894,7 @@ INTERNAL void sim_ent_sync_remote(struct sim_ent *local, struct sim_ent *remote)
 }
 
 
+/* Walks a local & remote ent tree and allocates net dst ents from remote src ents */
 INTERNAL void sim_ent_alloc_any_missing_net_dst(struct sim_ent *local_parent, struct sim_ent *remote)
 {
     __prof;
@@ -1899,10 +1903,10 @@ INTERNAL void sim_ent_alloc_any_missing_net_dst(struct sim_ent *local_parent, st
         struct sim_snapshot *remote_ss = remote->ss;
         struct sim_client_handle remote_client_handle = remote_ss->client->handle;
 
-        struct sim_netid netid = sim_ent_get_netid(remote);
-        struct sim_ent *local_ent = sim_ent_from_netid(local_ss, netid);
+        struct uid uid = sim_ent_get_uid(remote);
+        struct sim_ent *local_ent = sim_ent_from_uid(local_ss, uid);
         if (!local_ent->valid) {
-            local_ent = sim_ent_alloc_net_dst(local_parent, remote_client_handle, netid);
+            local_ent = sim_ent_alloc_net_dst(local_parent, remote_client_handle, uid);
         }
         for (struct sim_ent *remote_child = sim_ent_from_handle(remote_ss, remote->first); remote_child->valid; remote_child = sim_ent_from_handle(remote_ss, remote_child->next)) {
             sim_ent_alloc_any_missing_net_dst(local_ent, remote_child);
@@ -1911,7 +1915,7 @@ INTERNAL void sim_ent_alloc_any_missing_net_dst(struct sim_ent *local_parent, st
 }
 
 
-INTERNAL void sim_snapshot_sync_remote_ents(struct sim_snapshot *local_ss, struct sim_snapshot *remote_ss)
+INTERNAL void sim_snapshot_sync_net_ents(struct sim_snapshot *local_ss, struct sim_snapshot *remote_ss)
 {
     __prof;
 
@@ -1929,8 +1933,8 @@ INTERNAL void sim_snapshot_sync_remote_ents(struct sim_snapshot *local_ss, struc
     for (u64 i = 0; i < local_ss->num_ents_reserved; ++i) {
         struct sim_ent *local_ent = &local_ss->ents[i];
         if (local_ent->valid && sim_ent_has_prop(local_ent, SIM_ENT_PROP_NET_DST) && sim_client_handle_eq(local_ent->net_src_client, remote_client_handle)) {
-            struct sim_netid netid = sim_ent_get_netid(local_ent);
-            struct sim_ent *remote_ent = sim_ent_from_netid(remote_ss, netid);
+            struct uid uid = sim_ent_get_uid(local_ent);
+            struct sim_ent *remote_ent = sim_ent_from_uid(remote_ss, uid);
             if (remote_ent->valid) {
                 /* Copy all ent data from remote */
                 sim_ent_sync_remote(local_ent, remote_ent);
@@ -2178,7 +2182,7 @@ INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(user_local_sim_thread_entry_point, arg)
             {
                 struct sys_lock lock = sys_mutex_lock_e(&G.user_sim_cmd_mutex);
                 control_cmd_ent->cmd_control = G.user_sim_cmd_control;
-                control_cmd_ent->cmd_hovered_ent_netid = G.user_sim_cmd_hovered_ent_netid;
+                control_cmd_ent->cmd_hovered_ent_uid = G.user_sim_cmd_hovered_ent_uid;
                 ++G.user_sim_cmd_gen;
                 sys_mutex_unlock(&lock);
             }
@@ -2199,16 +2203,16 @@ INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(user_local_sim_thread_entry_point, arg)
                 if (client->valid) {
                     /* Create client ent if necessary */
                     if (is_master && client != publish_client && client != local_client && client != master_client) {
-                        struct sim_ent *client_ent = sim_ent_from_netid(local_ss, client->client_ent_netid);
+                        struct sim_ent *client_ent = sim_ent_from_uid(local_ss, client->ent_uid);
                         if (!client_ent->valid) {
                             /* FIXME: Client ent never released upon disconnect */
                             client_ent = sim_ent_alloc_net_src(local_root);
                             client_ent->client_handle = client->handle;
                             sim_ent_enable_prop(client_ent, SIM_ENT_PROP_CLIENT);
                             sim_ent_enable_prop(client_ent, SIM_ENT_PROP_ACTIVE);
-                            client->client_ent_netid = sim_ent_get_netid(client_ent);
+                            client->ent_uid = sim_ent_get_uid(client_ent);
                             if (client == user_input_client) {
-                                local_ss->local_client_netid = sim_ent_get_netid(client_ent);
+                                local_ss->local_client_ent_uid = sim_ent_get_uid(client_ent);
                             }
                         }
                     }
@@ -2218,9 +2222,9 @@ INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(user_local_sim_thread_entry_point, arg)
                     if (client != publish_client && client != local_client) {
                         struct sim_snapshot *client_ss = sim_snapshot_from_tick(client, step_tick);
                         if (client_ss->valid) {
-                            sim_snapshot_sync_remote_ents(local_ss, client_ss);
+                            sim_snapshot_sync_net_ents(local_ss, client_ss);
                             if (!is_master && client == master_client) {
-                                local_ss->local_client_netid = client_ss->local_client_netid;
+                                local_ss->local_client_ent_uid = client_ss->local_client_ent_uid;
                             }
                         }
                     }
@@ -2234,7 +2238,7 @@ INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(user_local_sim_thread_entry_point, arg)
                 struct sim_ent *ent = &local_ss->ents[i];
                 if (ent->valid && sim_ent_has_prop(ent, SIM_ENT_PROP_NET_DST)) {
                     struct sim_client *src_client = sim_client_from_handle(store, ent->net_src_client);
-                    struct sim_ent *client_ent = sim_ent_from_netid(local_ss, src_client->client_ent_netid);
+                    struct sim_ent *client_ent = sim_ent_from_uid(local_ss, src_client->ent_uid);
                     ent->cmd_client = client_ent->handle;
                 }
             }
@@ -2368,7 +2372,7 @@ INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(user_local_sim_thread_entry_point, arg)
             } else {
                 pub_ss = sim_snapshot_alloc(publish_client, sim_snapshot_from_tick(publish_client, publish_client->last_tick), local_ss->tick + 5);
             }
-            sim_snapshot_sync_remote_ents(pub_ss, local_ss);
+            sim_snapshot_sync_net_ents(pub_ss, local_ss);
         }
 #endif
 
@@ -2438,7 +2442,7 @@ INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(user_local_sim_thread_entry_point, arg)
              /* TODO: Double buffer */
             struct sys_lock lock = sys_mutex_lock_e(&G.local_to_user_client_mutex);
             struct sim_snapshot *copy_ss = sim_snapshot_alloc(G.local_to_user_client, local_ss, local_ss->tick);
-            copy_ss->local_client_netid = local_ss->local_client_netid;
+            copy_ss->local_client_ent_uid = local_ss->local_client_ent_uid;
             i64 publish_ns = sys_time_ns();
             copy_ss->publish_dt_ns = publish_ns - last_publish_ns;
             copy_ss->publish_time_ns = publish_ns;