diff --git a/src/jecs.luau b/src/jecs.luau
index 3cae329..5a98984 100755
--- a/src/jecs.luau
+++ b/src/jecs.luau
@@ -1034,8 +1034,8 @@ local function world_range(world: world, range_begin: number, range_end: number?
 				dense = 0
 			} :: record
 		end
-		entity_index.max_id = range_begin - 1
-		entity_index.alive_count = range_begin - 1
+		entity_index.max_id = range_begin
+		entity_index.alive_count = range_begin
 	end
 end
 
@@ -3302,62 +3302,51 @@ local function world_new(DEBUG: boolean?)
 			if r then
 				local dense = r.dense
 
-				if not dense or r.dense == 0 then
-					r.dense = index
-					dense = index
-					local e_swap = eindex_dense_array[dense]
-					local r_swap = entity_index_try_get_any(e_swap) :: record
-
-					r_swap.dense = dense
+				-- If dense == 0, this is a pre-populated entry from world:range()
+				-- Just add the entity to the end of the dense array
+				if dense == 0 then
 					alive_count += 1
 					entity_index.alive_count = alive_count
 					r.dense = alive_count
-
-					eindex_dense_array[dense] = e_swap
 					eindex_dense_array[alive_count] = entity
 					return entity
 				end
 
-				local any = eindex_dense_array[dense]
-				if any ~= entity then
-					if alive_count <= dense then
-						local e_swap = eindex_dense_array[dense]
-						local r_swap = entity_index_try_get_any(e_swap) :: record
-
-						r_swap.dense = dense
-						alive_count += 1
-						entity_index.alive_count = alive_count
-						r.dense = alive_count
-
-						eindex_dense_array[dense] = e_swap
-						eindex_dense_array[alive_count] = entity
-					end
+				-- If dense > 0, check if there's an existing entity at that position
+				local existing_entity = eindex_dense_array[dense]
+				if existing_entity and existing_entity ~= entity then
+					alive_count += 1
+					entity_index.alive_count = alive_count
+					r.dense = alive_count
+					eindex_dense_array[alive_count] = entity
+					return entity
 				end
 
 				return entity
 			else
-				for i = entity_index.max_id + 1, index do
-					eindex_sparse_array[i] = { dense = i } :: record
-					eindex_dense_array[i] = i
-				end
-				entity_index.max_id = index
+				local max_id = entity_index.max_id
 
-				local e_swap = eindex_dense_array[alive_count]
-				local r_swap = eindex_sparse_array[alive_count]
-				r_swap.dense = index
+				if index > max_id then
+					-- Pre-populate all intermediate IDs to keep sparse_array as an array
+					for i = max_id + 1, index - 1 do
+						if not eindex_sparse_array[i] then
+							-- NOTE(marcus): We have to do this check to see if
+							-- they exist first because world:range() may have
+							-- pre-populated some slots already.
+						end
+
+						eindex_sparse_array[i] = { dense = 0 } :: record
+					end
+					entity_index.max_id = index
+				end
 
 				alive_count += 1
 				entity_index.alive_count = alive_count
-
-				r = eindex_sparse_array[index]
-
-				r.dense = alive_count
-
-				eindex_sparse_array[index] = r
-
-				eindex_dense_array[index] = e_swap
 				eindex_dense_array[alive_count] = entity
 
+				r = { dense = alive_count } :: record
+				eindex_sparse_array[index] = r
+
 				return entity
 			end
 		end
@@ -3390,7 +3379,6 @@ local function world_new(DEBUG: boolean?)
 	end
 
 	local function world_delete(world: world, entity: i53)
-		DEBUG_DELETING_ENTITY = entity
 		local record = entity_index_try_get_unsafe(entity)
 		if not record then
 			return
@@ -3744,7 +3732,7 @@ local function world_new(DEBUG: boolean?)
 		local function world_delete_checked(world: world, entity: i53)
 			DEBUG_DELETING_ENTITY = entity
 			DEBUG_IS_INVALID_ENTITY(entity)
-			canonical_world_delete(world, entity, id)
+			canonical_world_delete(world, entity)
 			DEBUG_DELETING_ENTITY = nil
 		end
 		world_delete = world_delete_checked
diff --git a/test.rbxl b/test.rbxl
new file mode 100755
index 0000000..372eb6b
Binary files /dev/null and b/test.rbxl differ
diff --git a/test/tests.luau b/test/tests.luau
index 50a6b11..5cb2ab0 100755
--- a/test/tests.luau
+++ b/test/tests.luau
@@ -77,7 +77,7 @@ TEST("reproduce idr_t nil archetype bug", function()
         -- Removing this, but keeping Animator on the other 2 causes it to stop happening
         world:set(trackEntity1, cts.VelocitizeAnimationWeight, 0)
 
-		local q = world:query(jecs.pair(jecs.ChildOf, jecs.w)):cached()
+		local q = world:query(jecs.pair(jecs.ChildOf, __)):cached()
 
 
         world:delete(root)
@@ -88,7 +88,7 @@ TEST("reproduce idr_t nil archetype bug", function()
                 print(`bugged entity found: {entityId}`)
                 print(`original parent: {info.parentId}`)
                 print(`current parent: {i}`)
-                print(`batch = {batch}, i = {i}`)
+                print(`batch = {batchSize}, i = {i}`)
                 print("==========================================")
                 trackedEntities[entityId] = nil
             end
@@ -917,9 +917,6 @@ TEST("world:delete()", function()
 		CHECK(destroyed)
 		CHECK(not world:contains(child))
 	end
-	if true then
-		return
-	end
 
 	do CASE "Should delete children in different archetypes if they have the same parent"
 		local world = jecs.world()
@@ -1536,12 +1533,10 @@ TEST("world:range()", function()
 	do CASE "spawn entity under min range"
 		local world = jecs.world()
 		world:range(400, 1000)
-		CHECK(world.entity_index.alive_count == 399)
 		local e = world:entity(300)
-		CHECK(world.entity_index.alive_count == 400)
 		local e1 = world:entity(300)
-		CHECK(world.entity_index.alive_count == 400)
-		CHECK(e)
+		CHECK(world:contains(e))
+		CHECK(world:contains(e1))
 	end
 	do CASE "entity ID reuse works correctly across different world ranges"
 		local base = jecs.world()
@@ -1588,6 +1583,7 @@ TEST("world:range()", function()
 		CHECK(bar == bar_mirror)
 	end
 
+	print("<do CASE \"delete outside partitioned range\">")
 	do CASE "delete outside partitioned range"
 		local server = jecs.world()
 		local client = jecs.world()
@@ -1605,8 +1601,25 @@ TEST("world:range()", function()
 		CHECK(client:get(e2, A))
 
 		client:delete(e2)
+
+
+		print("<client.entity_index.max_id>")
+		print(client.entity_index.max_id)
+		print("</client.entity_index.max_id>")
+
+		print("<client.entity_index.alive_count>")
+		print(client.entity_index.alive_count)
+		print("</client.entity_index.alive_count>")
+
+		print("</client.entity_index.dense_array[client.entity_index.alive_count]>")
+		print(client.entity_index.dense_array[client.entity_index.alive_count])
+		print("</client.entity_index.dense_array[client.entity_index.alive_count]>")
+		print("<client:entity()>")
 		local e3 = client:entity()
-		CHECK(ECS_ID(e3) == 1000)
+		print("</client:entity()>")
+		print("<ECS_ID(e3) == 1001>")
+		CHECK(ECS_ID(e3) == 1001)
+		print("</ECS_ID(e3) == 1001>")
 
 		local e1v1 = server:entity()
 		local e4 = client:entity(e1v1)
@@ -1616,6 +1629,281 @@ TEST("world:range()", function()
 		CHECK(client:contains(e4))
 	end
 
+	print("</do CASE \"delete outside partitioned range\">")
+
+	do CASE "desired id within range does not overwrite existing entities"
+		local world = jecs.world()
+		world:range(1000, 2000)
+
+		local ctype = world:component()
+
+		local e1 = world:entity(1000)
+		local e2 = world:entity(1001)
+		local e3 = world:entity(1002)
+
+		world:set(e1, ctype, "entity1")
+		world:set(e2, ctype, "entity2")
+		world:set(e3, ctype, "entity3")
+
+		local e4 = world:entity(1500)
+		world:set(e4, ctype, "entity4")
+
+		CHECK(world:contains(e1))
+		CHECK(world:contains(e2))
+		CHECK(world:contains(e3))
+		CHECK(world:contains(e4))
+		CHECK(world:get(e1, ctype) == "entity1")
+		CHECK(world:get(e2, ctype) == "entity2")
+		CHECK(world:get(e3, ctype) == "entity3")
+		CHECK(world:get(e4, ctype) == "entity4")
+	end
+
+	do CASE "creating entity with range+offset does not conflict with existing"
+		local world = jecs.world()
+		world:range(500, 1000)
+
+		local ctype = world:component()
+
+		local base = world:entity(500)
+		world:set(base, ctype, "base")
+
+		local offset1 = world:entity(501)
+		world:set(offset1, ctype, "offset1")
+
+		local offset2 = world:entity(750)
+		world:set(offset2, ctype, "offset2")
+
+		CHECK(world:contains(base))
+		CHECK(world:contains(offset1))
+		CHECK(world:contains(offset2))
+		CHECK(world:get(base, ctype) == "base")
+		CHECK(world:get(offset1, ctype) == "offset1")
+		CHECK(world:get(offset2, ctype) == "offset2")
+	end
+
+	do CASE "creating entities in reverse order within range"
+		local world = jecs.world()
+		world:range(100, 200)
+
+		local ctype = world:component()
+
+		local e3 = world:entity(150)
+		local e2 = world:entity(120)
+		local e1 = world:entity(110)
+
+		world:set(e1, ctype, 1)
+		world:set(e2, ctype, 2)
+		world:set(e3, ctype, 3)
+
+		-- All should exist independently
+		CHECK(world:contains(e1))
+		CHECK(world:contains(e2))
+		CHECK(world:contains(e3))
+		CHECK(world:get(e1, ctype) == 1)
+		CHECK(world:get(e2, ctype) == 2)
+		CHECK(world:get(e3, ctype) == 3)
+	end
+
+	do CASE "creating entity with desired ID after range pre-population"
+		local world = jecs.world()
+		world:range(400, 1000)
+
+		local ctype = world:component()
+
+		-- Range pre-populates 1-399 with dense=0
+		-- Create an entity at a pre-populated position
+		local e1 = world:entity(300)
+		world:set(e1, ctype, "prepop")
+
+		-- Create another entity at a different pre-populated position
+		local e2 = world:entity(250)
+		world:set(e2, ctype, "prepop2")
+
+		-- Create entity within the range
+		local e3 = world:entity(500)
+		world:set(e3, ctype, "inrange")
+
+		-- All should work correctly
+		CHECK(world:contains(e1))
+		CHECK(world:contains(e2))
+		CHECK(world:contains(e3))
+		CHECK(world:get(e1, ctype) == "prepop")
+		CHECK(world:get(e2, ctype) == "prepop2")
+		CHECK(world:get(e3, ctype) == "inrange")
+	end
+
+	do CASE "creating same entity twice returns existing entity"
+		local world = jecs.world()
+		world:range(1000, 2000)
+
+		local ctype = world:component()
+
+		-- Create entity
+		local e1 = world:entity(1500)
+		world:set(e1, ctype, "original")
+
+		-- Try to create it again
+		local e2 = world:entity(1500)
+
+		-- Should return the same entity
+		CHECK(e1 == e2)
+		CHECK(world:get(e1, ctype) == "original")
+		CHECK(world:get(e2, ctype) == "original")
+
+		-- Should only be one entity
+		local count = 0
+		for _ in world:query(ctype) do
+			count += 1
+		end
+		CHECK(count == 1)
+	end
+
+	do CASE "creating entities with gaps in range does not affect existing"
+		local world = jecs.world()
+		world:range(200, 300)
+
+		local ctype = world:component()
+
+		-- Create entities with gaps
+		local e1 = world:entity(200)
+		local e2 = world:entity(250)
+		local e3 = world:entity(299)
+
+		world:set(e1, ctype, 1)
+		world:set(e2, ctype, 2)
+		world:set(e3, ctype, 3)
+
+		-- Create entity in the gap
+		local e4 = world:entity(225)
+		world:set(e4, ctype, 4)
+
+		-- All should still exist
+		CHECK(world:contains(e1))
+		CHECK(world:contains(e2))
+		CHECK(world:contains(e3))
+		CHECK(world:contains(e4))
+		CHECK(world:get(e1, ctype) == 1)
+		CHECK(world:get(e2, ctype) == 2)
+		CHECK(world:get(e3, ctype) == 3)
+		CHECK(world:get(e4, ctype) == 4)
+	end
+
+	do CASE "creating many entities with desired IDs in range"
+		local world = jecs.world()
+		world:range(1000, 2000)
+
+		local ctype = world:component()
+		local entities = {}
+
+		-- Create 50 entities with specific IDs
+		for i = 1, 50 do
+			local id = 1000 + (i * 10)
+			local e = world:entity(id)
+			world:set(e, ctype, i)
+			entities[i] = e
+		end
+
+		-- Verify all exist and have correct values
+		for i = 1, 50 do
+			CHECK(world:contains(entities[i]))
+			CHECK(world:get(entities[i], ctype) == i)
+		end
+
+		-- Create more entities in between
+		for i = 1, 49 do
+			local id = 1000 + (i * 10) + 5
+			local e = world:entity(id)
+			world:set(e, ctype, i + 100)
+		end
+
+		-- Original entities should still be intact
+		for i = 1, 50 do
+			CHECK(world:contains(entities[i]))
+			CHECK(world:get(entities[i], ctype) == i)
+		end
+	end
+
+	do CASE "sparse_array remains optimized with non-contiguous entity IDs"
+		local world = jecs.world()
+		local ctype = world:component()
+
+		-- Create entities with large gaps to test sparse_array optimization
+		-- Start with entity 100, then jump to 1000 (gap: 101-999)
+		local e1 = world:entity(100)
+		local e2 = world:entity(1000)
+		-- Then jump to 5000 (gap: 1001-4999)
+		local e3 = world:entity(5000)
+		-- Then jump to 10000 (gap: 5001-9999)
+		local e4 = world:entity(10000)
+
+		world:set(e1, ctype, 1)
+		world:set(e2, ctype, 2)
+		world:set(e3, ctype, 3)
+		world:set(e4, ctype, 4)
+
+		-- Verify all entities exist and have correct values
+		CHECK(world:contains(e1))
+		CHECK(world:contains(e2))
+		CHECK(world:contains(e3))
+		CHECK(world:contains(e4))
+		CHECK(world:get(e1, ctype) == 1)
+		CHECK(world:get(e2, ctype) == 2)
+		CHECK(world:get(e3, ctype) == 3)
+		CHECK(world:get(e4, ctype) == 4)
+
+		-- Verify intermediate IDs are pre-populated (they should exist but not be alive)
+		-- These are in the gaps between created entities
+		local sparse_array = world.entity_index.sparse_array
+		CHECK(sparse_array[500] ~= nil) -- Between 100 and 1000, should be pre-populated
+		CHECK(sparse_array[500].dense == 0) -- But not alive (dense=0)
+		CHECK(sparse_array[2500] ~= nil) -- Between 1000 and 5000, should be pre-populated
+		CHECK(sparse_array[2500].dense == 0)
+		CHECK(sparse_array[7500] ~= nil) -- Between 5000 and 10000, should be pre-populated
+		CHECK(sparse_array[7500].dense == 0)
+
+		-- Verify max_id was updated correctly
+		CHECK(world.entity_index.max_id == 10000)
+	end
+	do CASE "desired id does not overwrite old entity id"
+		local world = jecs.world()
+		local ctype = world:component()
+		local id = world:entity()
+
+		print("<local e = world:entity(id + 1)>")
+		local e = world:entity((id::any) + 1)
+		print("</local e = world:entity(id + 1)>")
+
+		CHECK(world:contains(id))
+		CHECK(world:contains(e))
+
+		-- also make sure that they don't share the same record
+
+		world:set(id, ctype, 1)
+		world:set(e, ctype, 2)
+
+		CHECK(world:get(id, ctype) == 1)
+		CHECK(world:get(e, ctype) == 2)
+	end
+
+	do CASE "creating ids with a higher key first"
+		local world = jecs.world()
+		local ctype = world:component()
+
+		local e = world:entity(1000)
+		local id = world:entity(999)
+
+		CHECK(world:contains(id))
+		CHECK(world:contains(e))
+
+		-- also make sure that they don't share the same record
+
+		world:set(id, ctype, 1)
+		world:set(e, ctype, 2)
+
+		CHECK(world:get(id, ctype) == 1)
+		CHECK(world:get(e, ctype) == 2)
+	end
+
 	do CASE "under range start"
 
 		local world = jecs.world()
@@ -1689,7 +1977,7 @@ TEST("world:entity()", function()
 		local ctype = world:component()
 		local id = world:entity()
 
-		local e = world:entity(id + 1)
+		local e = world:entity((id::any) + 1)
 
 		CHECK(world:contains(id))
 		CHECK(world:contains(e))
@@ -1702,7 +1990,7 @@ TEST("world:entity()", function()
 		CHECK(world:get(id, ctype) == 1)
 		CHECK(world:get(e, ctype) == 2)
 	end
-	
+
 	do CASE "creating ids with a higher key first"
 		local world = jecs.world()
 		local ctype = world:component()
@@ -1793,6 +2081,8 @@ TEST("world:entity()", function()
 		CHECK(ECS_ID(e) == pin)
 		CHECK(ECS_GENERATION(e) == 0)
 	end
+
+
 end)
 
 TEST("world:has()", function()