diff --git a/src/entity.c b/src/entity.c
index 9a169c97..b536b97b 100644
--- a/src/entity.c
+++ b/src/entity.c
@@ -7,3 +7,94 @@ READONLY struct entity _g_entity_nil = {
     .sprite_xform = XFORM_IDENT,
     .sprite_tint = COLOR_WHITE
 };
+
+/* ========================== *
+ * Store allocation
+ * ========================== */
+
+struct entity_store entity_store_alloc(void)
+{
+    struct entity_store store = { 0 };
+    store.arena = arena_alloc(GIGABYTE(64));
+    return store;
+}
+
+void entity_store_release(struct entity_store *store)
+{
+    arena_release(&store->arena);
+}
+
+void entity_store_copy_replace(struct entity_store *dest, struct entity_store *src)
+{
+    struct arena orig_arena = dest->arena;
+    MEMCPY_STRUCT(dest, src);
+    dest->arena = orig_arena;
+    arena_copy_replace(&dest->arena, &src->arena);
+}
+
+/* ========================== *
+ * Allocation
+ * ========================== */
+
+struct entity *entity_alloc(struct entity_store *store)
+{
+    struct entity *entity = NULL;
+    if (store->first_free.gen) {
+        /* Reuse from free list */
+        entity = entity_from_handle(store, store->first_free);
+        store->first_free = entity->next_free;
+        entity->next_free = (struct entity_handle) { 0 };
+    } else {
+        /* Make new */
+        u64 idx = store->count++;
+        entity = arena_push(&store->arena, struct entity);
+        *entity = *entity_nil();
+        entity->handle = (struct entity_handle) { .gen = 1, .idx = idx };
+    }
+    return entity;
+}
+
+void entity_release(struct entity_store *store, struct entity *entity)
+{
+    struct entity_handle handle = (struct entity_handle) { .gen = entity->handle.gen, .idx = entity->handle.idx };
+    *entity = *entity_nil();
+    entity->handle = handle;
+    entity->next_free = store->first_free;
+    store->first_free = handle;
+}
+
+
+/* ========================== *
+ * Lookup
+ * ========================== */
+
+/* Returns a valid entity or nil entity. Always safe to read result, need to check to write. */
+struct entity *entity_from_handle(struct entity_store *store, struct entity_handle handle)
+{
+    if (handle.idx < store->count) {
+        struct entity *entities = (struct entity *)store->arena.base;
+        struct entity *entity = &entities[handle.idx];
+        if (entity->handle.gen == handle.gen) {
+            return entity;
+        }
+    }
+    return entity_nil();
+}
+
+void entity_link(struct entity_store *store, struct entity *parent, struct entity *child)
+{
+    struct entity *first_child = entity_from_handle(store, parent->first);
+    struct entity *last_child = entity_from_handle(store, parent->last);
+
+    child->prev = last_child->handle;
+    child->parent = parent->handle;
+
+    if (last_child->valid) {
+        last_child->next = child->handle;
+    }
+    parent->last = child->handle;
+
+    if (!first_child->valid) {
+        parent->first = child->handle;
+    }
+}
diff --git a/src/entity.h b/src/entity.h
index 426914b6..2681c501 100644
--- a/src/entity.h
+++ b/src/entity.h
@@ -4,11 +4,6 @@
 #include "sheet.h"
 #include "mixer.h"
 
-struct entity_handle {
-    u64 idx;
-    u64 gen;
-};
-
 enum entity_prop {
     ENTITY_PROP_NONE,
 
@@ -25,6 +20,17 @@ enum entity_prop {
     ENTITY_PROP_COUNT
 };
 
+struct entity_handle {
+    u64 idx;
+    u64 gen;
+};
+
+struct entity_store {
+    struct arena arena;
+    u64 count;
+    struct entity_handle first_free;
+};
+
 struct entity {
     b32 valid;
     struct entity_handle handle;
@@ -91,9 +97,22 @@ struct entity {
     f32 camera_zoom;
 };
 
+struct entity_array {
+    struct entity *entities;
+    u64 count;
+};
+
+/* ========================== *
+ * Nil
+ * ========================== */
+
 extern READONLY struct entity _g_entity_nil;
 INLINE READONLY struct entity *entity_nil(void) { return &_g_entity_nil; }
 
+/* ========================== *
+ * Property helpers
+ * ========================== */
+
 INLINE void entity_enable_prop(struct entity *entity, enum entity_prop prop)
 {
     u64 index = prop / 64;
@@ -115,4 +134,19 @@ INLINE b32 entity_has_prop(struct entity *entity, enum entity_prop prop)
     return !!(entity->props[index] & ((u64)1 << bit));
 }
 
+/* ========================== *
+ * Entity functions
+ * ========================== */
+
+/* Entity store */
+struct entity_store entity_store_alloc(void);
+void entity_store_release(struct entity_store *store);
+void entity_store_copy_replace(struct entity_store *dest, struct entity_store *src);
+
+/* Entity */
+struct entity *entity_alloc(struct entity_store *store);
+void entity_release(struct entity_store *store, struct entity *entity);
+struct entity *entity_from_handle(struct entity_store *store, struct entity_handle handle);
+void entity_link(struct entity_store *store, struct entity *parent, struct entity *child);
+
 #endif
diff --git a/src/game.c b/src/game.c
index fe9e3190..cb35f8e6 100644
--- a/src/game.c
+++ b/src/game.c
@@ -81,16 +81,12 @@ INTERNAL void game_update(void)
 
     struct temp_arena scratch = scratch_begin_no_conflict();
 
-    ++L.world.tick_id;
-    L.world.dt = max_f64(0.0, (1.0 / GAME_FPS) * L.timescale);
-    L.world.time += L.world.dt;
-
     /* TODO: remove this (testing) */
     /* Initialize entities */
     static b32 run = 0;
     if (!run) {
         run = 1;
-        (UNUSED)world_link_entities;
+        (UNUSED)entity_link;
 
         /* Player ent */
         struct entity *player_ent;
@@ -99,7 +95,7 @@ INTERNAL void game_update(void)
             struct v2 size = V2(1, 1);
             f32 r = 0;
 
-            struct entity *e = world_alloc_entity(&L.world);
+            struct entity *e = entity_alloc(&L.world.entity_store);
             e->valid = true;
             e->rel_xform = XFORM_TRS(.t = pos, .r = r, .s = size);
 
@@ -152,7 +148,7 @@ INTERNAL void game_update(void)
             struct v2 size = V2(1, 1);
             f32 r = 0;
 
-            struct entity *e = world_alloc_entity(&L.world);
+            struct entity *e = entity_alloc(&L.world.entity_store);
             e->valid = true;
             e->rel_xform = XFORM_TRS(.t = pos, .r = r, .s = size);
 
@@ -192,11 +188,11 @@ INTERNAL void game_update(void)
             //entity_enable_prop(e, ENTITY_PROP_TEST);
             //entity_enable_prop(e, ENTITY_PROP_TEST_FOLLOW_MOUSE);
 
-            world_link_entities(&L.world, parent, e);
+            entity_link(&L.world.entity_store, parent, e);
 
             if (sys_rand_u32() % 2 == 0) {
-                u64 parent_idx = sys_rand_u32() % L.world.entities_count;
-                struct entity *rand_ent = world_entity_from_handle(&L.world, (struct entity_handle) { .idx = parent_idx, .gen = 1 });
+                u64 parent_idx = sys_rand_u32() % world_get_entities(&L.world).count;
+                struct entity *rand_ent = entity_from_handle(&L.world.entity_store, (struct entity_handle) { .idx = parent_idx, .gen = 1 });
                 if (rand_ent->valid) {
                     parent = rand_ent;
                 } else {
@@ -207,7 +203,7 @@ INTERNAL void game_update(void)
 
         /* Camera ent */
         {
-            struct entity *e = world_alloc_entity(&L.world);
+            struct entity *e = entity_alloc(&L.world.entity_store);
             e->valid = true;
             e->rel_xform = XFORM_IDENT;
 
@@ -219,6 +215,11 @@ INTERNAL void game_update(void)
         }
     }
 
+    ++L.world.tick_id;
+    L.world.dt = max_f64(0.0, (1.0 / GAME_FPS) * L.timescale);
+    L.world.time += L.world.dt;
+    struct entity_array entities_array = world_get_entities(&L.world);
+
     /* ========================== *
      * Process game cmds
      * ========================== */
@@ -244,10 +245,10 @@ INTERNAL void game_update(void)
 
             /* Clear level */
             case GAME_CMD_KIND_CLEAR_ALL: {
-                for (u64 i = 0; i < L.world.entities_count; ++i) {
-                    struct entity *ent = &L.world.entities[i];
+                for (u64 i = 0; i < entities_array.count; ++i) {
+                    struct entity *ent = &entities_array.entities[i];
                     if (ent->valid) {
-                        world_release_entity(&L.world, ent);
+                        entity_release(&L.world.entity_store, ent);
                     }
                 }
             } break;
@@ -268,8 +269,8 @@ INTERNAL void game_update(void)
      * Update entities pre-physics
      * ========================== */
 
-    for (u64 entity_index = 0; entity_index < L.world.entities_count; ++entity_index) {
-        struct entity *ent = &L.world.entities[entity_index];
+    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
+        struct entity *ent = &entities_array.entities[entity_index];
         if (!ent->valid) continue;
 
         /* ========================== *
@@ -337,8 +338,8 @@ INTERNAL void game_update(void)
      * Update entity physics
      * ========================== */
 
-    for (u64 entity_index = 0; entity_index < L.world.entities_count; ++entity_index) {
-        struct entity *ent = &L.world.entities[entity_index];
+    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
+        struct entity *ent = &entities_array.entities[entity_index];
         if (!ent->valid) continue;
         if (ent->parent.gen) continue;  /* Only update parent entities */
 
@@ -417,14 +418,14 @@ INTERNAL void game_update(void)
                 child->world_xform = world_xform;
 
                 /* Append sub-children to stack */
-                struct entity *subchild = world_entity_from_handle(&L.world, child->last);
+                struct entity *subchild = entity_from_handle(&L.world.entity_store, child->last);
                 while (subchild->valid) {
                     *arena_push(stack.arena, struct xform_stack_node) = (struct xform_stack_node) {
                         .entity = subchild,
                         .parent_xform = world_xform
                     };
                     ++stack_count;
-                    subchild = world_entity_from_handle(&L.world, subchild->prev);
+                    subchild = entity_from_handle(&L.world.entity_store, subchild->prev);
                 }
             }
 
@@ -436,8 +437,8 @@ INTERNAL void game_update(void)
      * Update entities post-physics
      * ========================== */
 
-    for (u64 entity_index = 0; entity_index < L.world.entities_count; ++entity_index) {
-        struct entity *ent = &L.world.entities[entity_index];
+    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
+        struct entity *ent = &entities_array.entities[entity_index];
         if (!ent->valid) continue;
 
         /* ========================== *
@@ -445,7 +446,7 @@ INTERNAL void game_update(void)
          * ========================== */
 
         if (entity_has_prop(ent, ENTITY_PROP_CAMERA)) {
-            struct entity *follow = world_entity_from_handle(&L.world, ent->camera_follow);
+            struct entity *follow = entity_from_handle(&L.world.entity_store, ent->camera_follow);
 
             ent->world_xform = follow->world_xform;
             ent->world_xform = xform_with_rotation(ent->world_xform, 0);
diff --git a/src/memory.h b/src/memory.h
index 47825d9f..16b09c1b 100644
--- a/src/memory.h
+++ b/src/memory.h
@@ -5,7 +5,9 @@
 #define MEMZERO_ARRAY(a) MEMZERO(a, sizeof(a))
 #define MEMZERO(ptr, count) MEMSET(ptr, 0, count)
 
+#define MEMCPY_STRUCT(ptr_dest, ptr_src) MEMCPY(ptr_dest, ptr_src, sizeof(*ptr_dest));
 #define MEMCPY(dest, src, count) memcpy(dest, src, count)
+
 #define MEMSET(ptr, val, count) memset(ptr, val, count)
 
 
diff --git a/src/user.c b/src/user.c
index 074bf484..6daae5be 100644
--- a/src/user.c
+++ b/src/user.c
@@ -516,11 +516,15 @@ INTERNAL void user_update(void)
         L.world.time = math_lerp_f64(t0->time, t1->time, (f64)tick_blend);
 
         /* Blend entities */
-        u64 num_entities = min_u64(t0->entities_count, t1->entities_count);
+        struct entity_array t0_entities = world_get_entities(t0);
+        struct entity_array t1_entities = world_get_entities(t1);
+        struct entity_array world_entities = world_get_entities(&L.world);
+
+        u64 num_entities = min_u64(t0_entities.count, t1_entities.count);
         for (u64 i = 0; i < num_entities; ++i) {
-            struct entity *e0 = &t0->entities[i];
-            struct entity *e1 = &t1->entities[i];
-            struct entity *e = &L.world.entities[i];
+            struct entity *e0 = &t0_entities.entities[i];
+            struct entity *e1 = &t1_entities.entities[i];
+            struct entity *e = &world_entities.entities[i];
             if (e0->handle.gen == e1->handle.gen && e0->continuity_gen == e1->continuity_gen) {
                 e->rel_xform = xform_lerp(e0->rel_xform, e1->rel_xform, tick_blend);
                 e->world_xform = xform_lerp(e0->world_xform, e1->world_xform, tick_blend);
@@ -540,13 +544,15 @@ INTERNAL void user_update(void)
 #endif
     }
 
+    struct entity_array entities_array = world_get_entities(&L.world);
+
     /* ========================== *
      * Update view from game camera
      * ========================== */
 
     /* Find camera */
-    for (u64 entity_index = 0; entity_index < L.world.entities_count; ++entity_index) {
-        struct entity *ent = &L.world.entities[entity_index];
+    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
+        struct entity *ent = &entities_array.entities[entity_index];
         if (!ent->valid) continue;
 
         if (entity_has_prop(ent, ENTITY_PROP_CAMERA) && ent->camera_active && !L.debug_camera) {
@@ -606,10 +612,10 @@ INTERNAL void user_update(void)
      * ========================== */
 
     /* Iterate entities */
-    for (u64 entity_index = 0; entity_index < L.world.entities_count; ++entity_index) {
+    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
         __profscope(user_entity_iter);
 
-        struct entity *ent = &L.world.entities[entity_index];
+        struct entity *ent = &entities_array.entities[entity_index];
         if (!ent->valid) continue;
 
         b32 is_camera = entity_has_prop(ent, ENTITY_PROP_CAMERA);
@@ -721,7 +727,7 @@ INTERNAL void user_update(void)
             debug_draw_movement(ent);
 
             /* Draw hierarchy */
-            struct entity *parent = world_entity_from_handle(&L.world, ent->parent);
+            struct entity *parent = entity_from_handle(&L.world.entity_store, ent->parent);
             if (parent->valid) {
                 u32 color = RGBA_F(0.6, 0.6, 1, 0.75);
                 f32 thickness = 5;
diff --git a/src/world.c b/src/world.c
index 77e6648f..0d520bc2 100644
--- a/src/world.c
+++ b/src/world.c
@@ -1,97 +1,32 @@
 #include "world.h"
 #include "entity.h"
-
-/* ========================== *
- * World allocation
- * ========================== */
+#include "arena.h"
+#include "scratch.h"
 
 void world_alloc(struct world *world)
 {
     MEMZERO_STRUCT(world);
-    world->entities_arena = arena_alloc(GIGABYTE(64));
-    world->entities = (struct entity *)world->entities_arena.base;
+    world->entity_store = entity_store_alloc();
 }
 
 void world_copy_replace(struct world *dest, struct world *src)
 {
     __prof;
+    struct temp_arena scratch = scratch_begin_no_conflict();
+    struct world *old = arena_push(scratch.arena, struct world);
+    *old = *dest;
 
-    /* Copy non-arena fields */
-    MEMCPY(dest, src, FIELD_OFFSETOF(struct world, _copy_barrier));
+    MEMCPY_STRUCT(dest, src);
+    dest->entity_store = old->entity_store;
+    entity_store_copy_replace(&dest->entity_store, &src->entity_store);
 
-    /* Copy arena contents */
-    arena_copy_replace(&dest->entities_arena, &src->entities_arena);
+    scratch_end(scratch);
 }
 
-/* ========================== *
- * Entity allocation
- * ========================== */
-
-struct entity *world_alloc_entity(struct world *world)
+struct entity_array world_get_entities(struct world *world)
 {
-    struct entity *entity = NULL;
-    struct entity_handle handle;
-    if (world->first_free_entity.gen) {
-        /* Reuse from free list */
-        entity = world_entity_from_handle(world, world->first_free_entity);
-        world->first_free_entity = entity->next_free;
-        handle = entity->handle;
-    } else {
-        /* Make new */
-        u64 idx = world->entities_count++;
-        entity = arena_push(&world->entities_arena, struct entity);
-        handle = (struct entity_handle) { .gen = 1, .idx = idx };
-    }
-    *entity = *entity_nil();
-    entity->handle = handle;
-    return entity;
-}
-
-void world_release_entity(struct world *world, struct entity *entity)
-{
-    struct entity_handle next_free = world->first_free_entity;
-    world->first_free_entity = entity->handle;
-    *entity = (struct entity) {
-        .handle.gen = entity->handle.gen + 1,
-        .next_free = next_free
+    return (struct entity_array) {
+        .entities = (struct entity *)world->entity_store.arena.base,
+        .count = world->entity_store.count
     };
 }
-
-/* ========================== *
- * Queries
- * ========================== */
-
-/* Returns a valid entity or nil entity. Always safe to read result, need to check to write. */
-struct entity *world_entity_from_handle(struct world *world, struct entity_handle handle)
-{
-    if (handle.idx < world->entities_count) {
-        struct entity *entities = world->entities;
-        struct entity *entity = &entities[handle.idx];
-        if (entity->handle.gen == handle.gen) {
-            return entity;
-        }
-    }
-    return entity_nil();
-}
-
-/* ========================== *
- * Tree
- * ========================== */
-
-void world_link_entities(struct world *world, struct entity *parent, struct entity *child)
-{
-    struct entity *first_child = world_entity_from_handle(world, parent->first);
-    struct entity *last_child = world_entity_from_handle(world, parent->last);
-
-    child->prev = last_child->handle;
-    child->parent = parent->handle;
-
-    if (last_child->valid) {
-        last_child->next = child->handle;
-    }
-    parent->last = child->handle;
-
-    if (!first_child->valid) {
-        parent->first = child->handle;
-    }
-}
diff --git a/src/world.h b/src/world.h
index 2494a6df..256ded9b 100644
--- a/src/world.h
+++ b/src/world.h
@@ -13,25 +13,11 @@ struct world {
     struct v2 player_move_dir;  /* Player movement direction */
     struct v2 player_focus; /* Mouse cursor pos in world coordinates */
 
-    u64 entities_count;  /* Includes 'released' & inactive entities */
-    struct entity_handle first_free_entity;
-
-    /* ====================================================================== */
-    /* Everything after this field is not dumb-MEMCPY'd by world_copy_replace */
-    u8 _copy_barrier;
-
-    /* Entities array */
-    struct arena entities_arena;
-    struct entity *entities;
+    struct entity_store entity_store;
 };
 
 void world_alloc(struct world *world);
 void world_copy_replace(struct world *dest, struct world *src);
-
-struct entity *world_alloc_entity(struct world *world);
-void world_release_entity(struct world *world, struct entity *entity);
-struct entity *world_entity_from_handle(struct world *world, struct entity_handle handle);
-
-void world_link_entities(struct world *world, struct entity *parent, struct entity *child);
+struct entity_array world_get_entities(struct world *world);
 
 #endif