diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8c1e21b704..f09d73c631 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@
 - `CustomSpatialOSSendSystem` is no longer available. [#1308](https://github.com/spatialos/gdk-for-unity/pull/1308)
 - The Player Lifecycle feature module now provides an `EntityId` in its `CreatePlayerEntityTemplate` callback. [#1315](https://github.com/spatialos/gdk-for-unity/pull/1315)
     - You will have to change your callback from `(string clientWorkerId, byte[] serializedArguments)` to `(EntityId entityId, string clientWorkerId, byte[] serializedArguments)`.
+- Added the `ComponentType[] MiniumComponentTypes { get; }` property to `IEntityGameObjectCreator`. [#1330](https://github.com/spatialos/gdk-for-unity/pull/1330)
+    - You will have to define the minimum set of components required on an entity to trigger the `OnEntityCreated` method on your custom GameObject creator.
 
 ### Added
 
@@ -32,6 +34,8 @@
 - Downgraded the level of several code generator logs from `Info` to `Trace`. [#1277](https://github.com/spatialos/gdk-for-unity/pull/1277)
 - Upgraded the Worker SDK to `14.5.0`. [#1317](https://github.com/spatialos/gdk-for-unity/pull/1317)
 - Upgraded the Platform SDK used by the Deployment Launcher to `14.5.0` [#1317](https://github.com/spatialos/gdk-for-unity/pull/1317)
+- Changed the GameObject Creation module to run for entities that match the minimum component set required by the creator, instead of any entity that is newly added.
+    - This means that the module no longer cares if an entity is checked out in one frame or across multiple.
 
 ### Fixed
 
@@ -59,6 +63,7 @@
 - The Playground project now uses QBI instead of CBI. [#1370](https://github.com/spatialos/gdk-for-unity/pull/1307)
 - Added `MockWorld` and `MockBase` classes to the `Improbable.Gdk.TestUtils` package. These are designed as a framework for testing Core code. [#1305](https://github.com/spatialos/gdk-for-unity/pull/1305)
 - Switched internal profiling to use new `ProfilerMarker` API. [#1311](https://github.com/spatialos/gdk-for-unity/pull/1311)
+- Changed `MockWorld.Options.AdditionalSystems` from `Type[]` to `Action<World>`. [#1330](https://github.com/spatialos/gdk-for-unity/pull/1330)
 
 ## `0.3.3` - 2020-02-14
 
diff --git a/UPGRADE_GUIDE.md b/UPGRADE_GUIDE.md
index 4a29ac49e0..2723380f82 100644
--- a/UPGRADE_GUIDE.md
+++ b/UPGRADE_GUIDE.md
@@ -29,6 +29,22 @@ public static EntityTemplate Player(EntityId entityId, string workerId, byte[] a
 }
 ```
 
+### The `IEntityGameObjectCreator` now requires the `ComponentType[] MiniumComponentTypes { get; }` property
+
+If you have written custom GameObject creators implementing `IEntityGameObjectCreator`, you will have to define the minimum set of components required on an entity to trigger the `OnEntityCreated` method.
+
+For example, the following has been added to the `GameObjectCreatorFromMetadata` class:
+
+```csharp
+public ComponentType[] MinimumComponentTypes { get; } =
+{
+    ComponentType.ReadOnly<Metadata.Component>(),
+    ComponentType.ReadOnly<Position.Component>()
+};
+```
+
+> You will need to add `using Unity.Entities;` to the top of the file and reference it in the assembly that your custom GameObject creator is in.
+
 ## From `0.3.2` to `0.3.3`
 
 ### Building for Android now requires the NDK
@@ -97,7 +113,7 @@ type Vector3d {
 You should then replace the import of `improbable/vector.schema` and usage of `improbable.Vector3f`/`improbable.Vector3d` with the schema file you defined.
 
 > Note that methods such as `Vector3f.ToUnityVector();` are no longer available and you'll need to reimplement them yourself as extension/static methods. You can find the old implementations here: [`Vector3f`](https://github.com/spatialos/gdk-for-unity/blob/0.2.6/workers/unity/Packages/io.improbable.gdk.tools/.CodeGenerator/GdkCodeGenerator/Partials/Improbable.Vector3f) and [`Vector3d`](https://github.com/spatialos/gdk-for-unity/blob/0.2.6/workers/unity/Packages/io.improbable.gdk.tools/.CodeGenerator/GdkCodeGenerator/Partials/Improbable.Vector3d).
-> 
+>
 > You will be unable to reimplement the operators since C# lacks the ability to define operations via extension methods.
 >
 > Note that the `Coordinates` type can be used as a replacement for `Vector3d` as they are structurally the same.
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectCreatorFromMetadata.cs b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectCreatorFromMetadata.cs
index e3a203e5de..490692fa68 100644
--- a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectCreatorFromMetadata.cs
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectCreatorFromMetadata.cs
@@ -3,6 +3,7 @@
 using System.IO;
 using Improbable.Gdk.Core;
 using Improbable.Gdk.Subscriptions;
+using Unity.Entities;
 using UnityEngine;
 using Object = UnityEngine.Object;
 
@@ -27,6 +28,12 @@ private readonly Dictionary<string, GameObject> cachedPrefabs
             typeof(MeshRenderer)
         };
 
+        public ComponentType[] MinimumComponentTypes { get; } =
+        {
+            ComponentType.ReadOnly<Metadata.Component>(),
+            ComponentType.ReadOnly<Position.Component>()
+        };
+
         public GameObjectCreatorFromMetadata(string workerType, Vector3 workerOrigin, ILogDispatcher logger)
         {
             this.workerType = workerType;
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitSystemStateComponent.cs b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitSystemStateComponent.cs
new file mode 100644
index 0000000000..8f649b4dd4
--- /dev/null
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitSystemStateComponent.cs
@@ -0,0 +1,10 @@
+using Improbable.Gdk.Core;
+using Unity.Entities;
+
+namespace Improbable.Gdk.GameObjectCreation
+{
+    public struct GameObjectInitSystemStateComponent : ISystemStateComponentData
+    {
+        public EntityId EntityId;
+    }
+}
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitSystemStateComponent.cs.meta b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitSystemStateComponent.cs.meta
new file mode 100644
index 0000000000..5d041edfc5
--- /dev/null
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitSystemStateComponent.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: d8c08a9c6deb7ee49bea161d49c872cb
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitializationSystem.cs b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitializationSystem.cs
index 203f0dc3a2..e957548f96 100644
--- a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitializationSystem.cs
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/GameObjectInitializationSystem.cs
@@ -1,3 +1,4 @@
+using System.Linq;
 using Improbable.Gdk.Core;
 using Improbable.Gdk.Subscriptions;
 using Unity.Entities;
@@ -21,12 +22,27 @@ internal class GameObjectInitializationSystem : ComponentSystem
         private readonly GameObject workerGameObject;
 
         private EntitySystem entitySystem;
-        private WorkerSystem workerSystem;
+
+        private EntityQuery newEntitiesQuery;
+        private EntityQuery removedEntitiesQuery;
+
+        private ComponentType[] minimumComponentSet = new[]
+        {
+            ComponentType.ReadOnly<SpatialEntityId>()
+        };
 
         public GameObjectInitializationSystem(IEntityGameObjectCreator gameObjectCreator, GameObject workerGameObject)
         {
             this.gameObjectCreator = gameObjectCreator;
             this.workerGameObject = workerGameObject;
+
+            var minCreatorComponentSet = gameObjectCreator.MinimumComponentTypes;
+            if (minCreatorComponentSet != null)
+            {
+                minimumComponentSet = minimumComponentSet
+                    .Concat(minCreatorComponentSet)
+                    .ToArray();
+            }
         }
 
         protected override void OnCreate()
@@ -34,7 +50,6 @@ protected override void OnCreate()
             base.OnCreate();
 
             entitySystem = World.GetExistingSystem<EntitySystem>();
-            workerSystem = World.GetExistingSystem<WorkerSystem>();
 
             Linker = new EntityGameObjectLinker(World);
 
@@ -42,10 +57,24 @@ protected override void OnCreate()
             {
                 Linker.LinkGameObjectToSpatialOSEntity(new EntityId(0), workerGameObject);
             }
+
+            newEntitiesQuery = GetEntityQuery(new EntityQueryDesc()
+            {
+                All = minimumComponentSet,
+                None = new[] { ComponentType.ReadOnly<GameObjectInitSystemStateComponent>() }
+            });
+
+            removedEntitiesQuery = GetEntityQuery(new EntityQueryDesc()
+            {
+                All = new[] { ComponentType.ReadOnly<GameObjectInitSystemStateComponent>() },
+                None = minimumComponentSet
+            });
         }
 
         protected override void OnDestroy()
         {
+            EntityManager.RemoveComponent<GameObjectInitSystemStateComponent>(GetEntityQuery(typeof(GameObjectInitSystemStateComponent)));
+
             Linker.UnlinkAllGameObjects();
 
             foreach (var entityId in entitySystem.GetEntitiesInView())
@@ -58,24 +87,24 @@ protected override void OnDestroy()
 
         protected override void OnUpdate()
         {
-            foreach (var entityId in entitySystem.GetEntitiesAdded())
+            Entities.With(newEntitiesQuery).ForEach((Entity entity, ref SpatialEntityId spatialEntityId) =>
             {
-                var entity = workerSystem.GetEntity(entityId);
                 gameObjectCreator.OnEntityCreated(new SpatialOSEntity(entity, EntityManager), Linker);
-            }
+                PostUpdateCommands.AddComponent(entity, new GameObjectInitSystemStateComponent
+                {
+                    EntityId = spatialEntityId.EntityId
+                });
+            });
 
-            var removedEntities = entitySystem.GetEntitiesRemoved();
-            foreach (var entityId in removedEntities)
+            Entities.With(removedEntitiesQuery).ForEach((ref GameObjectInitSystemStateComponent state) =>
             {
-                Linker.UnlinkAllGameObjectsFromEntityId(entityId);
-            }
+                Linker.UnlinkAllGameObjectsFromEntityId(state.EntityId);
+                gameObjectCreator.OnEntityRemoved(state.EntityId);
+            });
 
             Linker.FlushCommandBuffer();
 
-            foreach (var entityId in removedEntities)
-            {
-                gameObjectCreator.OnEntityRemoved(entityId);
-            }
+            EntityManager.RemoveComponent<GameObjectInitSystemStateComponent>(removedEntitiesQuery);
         }
     }
 }
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/IEntityGameObjectCreator.cs b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/IEntityGameObjectCreator.cs
index f230c54b1b..591370361a 100644
--- a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/IEntityGameObjectCreator.cs
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/IEntityGameObjectCreator.cs
@@ -1,7 +1,6 @@
 using Improbable.Gdk.Core;
-using Improbable.Worker.CInterop;
 using Improbable.Gdk.Subscriptions;
-using UnityEngine;
+using Unity.Entities;
 
 namespace Improbable.Gdk.GameObjectCreation
 {
@@ -11,6 +10,11 @@ namespace Improbable.Gdk.GameObjectCreation
     /// </summary>
     public interface IEntityGameObjectCreator
     {
+        /// <summary>
+        ///     The minimum set of components required on an entity to create a GameObject.
+        /// </summary>
+        ComponentType[] MinimumComponentTypes { get; }
+
         /// <summary>
         ///     Called when a new SpatialOS Entity is checked out by the worker.
         /// </summary>
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/GameObjectCreationTests.cs b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/GameObjectCreationTests.cs
new file mode 100644
index 0000000000..7d5bf6a45c
--- /dev/null
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/GameObjectCreationTests.cs
@@ -0,0 +1,152 @@
+using System.Collections.Generic;
+using Improbable.Gdk.Core;
+using Improbable.Gdk.Subscriptions;
+using Improbable.Gdk.TestUtils;
+using NUnit.Framework;
+using Unity.Entities;
+using UnityEngine;
+using Object = UnityEngine.Object;
+
+namespace Improbable.Gdk.GameObjectCreation.EditmodeTests
+{
+    public class GameObjectCreationTests : MockBase
+    {
+        private long entityId = 100;
+
+        private const string WorkerType = "TestWorkerType";
+
+        private EntityGameObjectLinker linker;
+
+        protected override MockWorld.Options GetOptions()
+        {
+            return new MockWorld.Options
+            {
+                AdditionalSystems = world =>
+                {
+                    var testGameObjectCreator = new TestGameObjectCreator(WorkerType);
+                    GameObjectCreationHelper.EnableStandardGameObjectCreation(world, testGameObjectCreator);
+                }
+            };
+        }
+
+        [SetUp]
+        public new void Setup()
+        {
+            base.Setup();
+
+            var goInitSystem = World.GetSystem<GameObjectInitializationSystem>();
+            linker = goInitSystem.Linker;
+        }
+
+        [TearDown]
+        public new void TearDown()
+        {
+            World.Dispose();
+        }
+
+        [Test]
+        public void Create_GameObject_after_required_components_arrive_in_same_frame()
+        {
+            World
+                .Step(world =>
+                {
+                    world.Connection.CreateEntity(entityId, new EntityTemplate());
+
+                    world.Connection.AddComponent(entityId, Position.ComponentId,
+                        new Position.Update { Coords = Coordinates.Zero });
+
+                    world.Connection.AddComponent(entityId, Metadata.ComponentId,
+                        new Metadata.Update { EntityType = "TestObject" });
+
+                    var gameObjectExists = linker.EntityIdToGameObjects
+                        .TryGetValue(new EntityId(entityId), out var gameObjects);
+
+                    Assert.IsFalse(gameObjectExists);
+                })
+                .Step(world =>
+                {
+                    var gameObjectExists = linker.EntityIdToGameObjects
+                        .TryGetValue(new EntityId(entityId), out var gameObjects);
+
+                    Assert.IsTrue(gameObjectExists);
+                });
+        }
+
+        [Test]
+        public void Create_GameObject_after_required_components_arrive_in_multiple_frames()
+        {
+            World
+                .Step(world =>
+                {
+                    world.Connection.CreateEntity(entityId, new EntityTemplate());
+                })
+                .Step(world =>
+                {
+                    world.Connection.AddComponent(entityId, Position.ComponentId,
+                        new Position.Update { Coords = Coordinates.Zero });
+
+                    var gameObjectExists = linker.EntityIdToGameObjects
+                        .TryGetValue(new EntityId(entityId), out var gameObjects);
+
+                    Assert.IsFalse(gameObjectExists);
+                })
+                .Step(world =>
+                {
+                    world.Connection.AddComponent(entityId, Metadata.ComponentId,
+                        new Metadata.Update { EntityType = "TestObject" });
+
+                    var gameObjectExists = linker.EntityIdToGameObjects
+                        .TryGetValue(new EntityId(entityId), out var gameObjects);
+
+                    Assert.IsFalse(gameObjectExists);
+                })
+                .Step(world =>
+                {
+                    var gameObjectExists = linker.EntityIdToGameObjects
+                        .TryGetValue(new EntityId(entityId), out var gameObjects);
+
+                    Assert.IsTrue(gameObjectExists);
+                });
+        }
+
+        private class TestGameObjectCreator : IEntityGameObjectCreator
+        {
+            private readonly string workerType;
+
+            private readonly Dictionary<EntityId, GameObject> entityIdToGameObject = new Dictionary<EntityId, GameObject>();
+
+            public ComponentType[] MinimumComponentTypes { get; } =
+            {
+                ComponentType.ReadOnly<Position.Component>(),
+                ComponentType.ReadOnly<Metadata.Component>()
+            };
+
+            public TestGameObjectCreator(string workerType)
+            {
+                this.workerType = workerType;
+            }
+
+            public void OnEntityCreated(SpatialOSEntity entity, EntityGameObjectLinker linker)
+            {
+                var gameObject = new GameObject();
+                gameObject.transform.position = Vector3.one;
+                gameObject.transform.rotation = Quaternion.identity;
+                gameObject.name = $"TestObject(SpatialOS: {entity.SpatialOSEntityId}, Worker: {workerType})";
+
+                entityIdToGameObject.Add(entity.SpatialOSEntityId, gameObject);
+                linker.LinkGameObjectToSpatialOSEntity(entity.SpatialOSEntityId, gameObject);
+            }
+
+            public void OnEntityRemoved(EntityId entityId)
+            {
+                if (!entityIdToGameObject.TryGetValue(entityId, out var go))
+                {
+                    return;
+                }
+
+                Object.DestroyImmediate(go);
+                entityIdToGameObject.Remove(entityId);
+            }
+        }
+    }
+}
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/GameObjectCreationTests.cs.meta b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/GameObjectCreationTests.cs.meta
new file mode 100644
index 0000000000..a2ece31a88
--- /dev/null
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/GameObjectCreationTests.cs.meta
@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 62932c56e25d424dafbb2d06dd8850e4
+timeCreated: 1584709255
\ No newline at end of file
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/Improbable.Gdk.GameObjectCreation.EditmodeTests.asmdef b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/Improbable.Gdk.GameObjectCreation.EditmodeTests.asmdef
index 23438866b4..1b266a25b3 100644
--- a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/Improbable.Gdk.GameObjectCreation.EditmodeTests.asmdef
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/Improbable.Gdk.GameObjectCreation.EditmodeTests.asmdef
@@ -1,12 +1,14 @@
 {
     "name": "Improbable.Gdk.GameObjectCreation.EditmodeTests",
     "references": [
-        "GUID:0603bcb6cd766ea40a053a38fff8a84b",
-        "GUID:edb3612c44ad0d24988d387581fd5fbe",
-        "GUID:6e87be7cacbd7264c9a5b9efc59a4030",
-        "GUID:734d92eba21c94caba915361bd5ac177",
-        "GUID:27619889b8ba8c24980f49ee34dbb44a",
-        "GUID:0acc523941302664db1f4e527237feb3"
+        "Improbable.Gdk.Core.EditmodeTests",
+        "Improbable.Gdk.Core",
+        "Improbable.Gdk.GameObjectCreation",
+        "Unity.Entities",
+        "UnityEngine.TestRunner",
+        "UnityEditor.TestRunner",
+        "Improbable.Gdk.TestUtils",
+        "Improbable.Gdk.Generated"
     ],
     "includePlatforms": [
         "Editor"
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/LinkedGameObjectMapSubscriptionTests.cs b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/LinkedGameObjectMapSubscriptionTests.cs
index 7163513438..3046d0eaa1 100644
--- a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/LinkedGameObjectMapSubscriptionTests.cs
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/LinkedGameObjectMapSubscriptionTests.cs
@@ -1,29 +1,48 @@
 using Improbable.Gdk.Core;
-using Improbable.Gdk.Core.EditmodeTests.Subscriptions;
 using Improbable.Gdk.Subscriptions;
+using Improbable.Gdk.TestUtils;
 using NUnit.Framework;
 
 namespace Improbable.Gdk.GameObjectCreation.EditmodeTests
 {
-    public class LinkedGameObjectMapSubscriptionTests : SubscriptionTestBase
+    public class LinkedGameObjectMapSubscriptionTests : MockBase
     {
         private EntityId entityId = new EntityId(100);
 
         [Test]
         public void Subscribe_to_LinkedGameObjectMap_should_not_be_available_if_GameObjectCreation_systems_are_not_present()
         {
-            var goMapSubscription = SubscriptionSystem.Subscribe<LinkedGameObjectMap>(entityId);
-            Assert.IsFalse(goMapSubscription.HasValue);
+            World
+                .Step((world) =>
+                {
+                    var subscriptionSystem = world.GetSystem<SubscriptionSystem>();
+                    var goMapSubscription = subscriptionSystem.Subscribe<LinkedGameObjectMap>(entityId);
+
+                    return goMapSubscription;
+                })
+                .Step((world, goMapSubscription) =>
+                {
+                    Assert.IsFalse(goMapSubscription.HasValue);
+                });
         }
 
         [Test]
         public void Subscribe_to_LinkedGameObjectMap_should_be_available_if_GameObjectCreation_systems_are_added()
         {
-            GameObjectCreationHelper.EnableStandardGameObjectCreation(World, new MockGameObjectCreator());
+            World
+                .Step((world) =>
+                {
+                    GameObjectCreationHelper.EnableStandardGameObjectCreation(world.Worker.World, new MockGameObjectCreator());
+                    var subscriptionSystem = world.GetSystem<SubscriptionSystem>();
+                    var goMapSubscription = subscriptionSystem.Subscribe<LinkedGameObjectMap>(entityId);
 
-            var goMapSubscription = SubscriptionSystem.Subscribe<LinkedGameObjectMap>(entityId);
-            Assert.IsTrue(goMapSubscription.HasValue);
-            Assert.IsNotNull(goMapSubscription.Value);
+                    return goMapSubscription;
+                })
+                .Step((world, goMapSubscription) =>
+                {
+                    Assert.IsTrue(goMapSubscription.HasValue);
+                    Assert.IsNotNull(goMapSubscription.Value);
+                });
         }
     }
 }
diff --git a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/MockGameObjectCreator.cs b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/MockGameObjectCreator.cs
index 2da4f5d62f..6b942931fd 100644
--- a/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/MockGameObjectCreator.cs
+++ b/workers/unity/Packages/io.improbable.gdk.gameobjectcreation/Tests/Editmode/MockGameObjectCreator.cs
@@ -1,10 +1,14 @@
+using System;
 using Improbable.Gdk.Core;
 using Improbable.Gdk.Subscriptions;
+using Unity.Entities;
 
 namespace Improbable.Gdk.GameObjectCreation.EditmodeTests
 {
     public class MockGameObjectCreator : IEntityGameObjectCreator
     {
+        public ComponentType[] MinimumComponentTypes { get; } = { };
+
         public void OnEntityCreated(SpatialOSEntity entity, EntityGameObjectLinker linker)
         {
             throw new System.NotImplementedException();
diff --git a/workers/unity/Packages/io.improbable.gdk.testutils/MockWorld.cs b/workers/unity/Packages/io.improbable.gdk.testutils/MockWorld.cs
index fd2fba3e6e..abb5c5c5ed 100644
--- a/workers/unity/Packages/io.improbable.gdk.testutils/MockWorld.cs
+++ b/workers/unity/Packages/io.improbable.gdk.testutils/MockWorld.cs
@@ -1,7 +1,9 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using Improbable.Gdk.Core;
 using Improbable.Gdk.Subscriptions;
+using NUnit.Framework;
 using Unity.Entities;
 using UnityEditor;
 using UnityEngine;
@@ -13,7 +15,7 @@ public class MockWorld : IDisposable
         public struct Options
         {
             public string WorkerType;
-            public Type[] AdditionalSystems;
+            public Action<World> AdditionalSystems;
             public ILogDispatcher Logger;
         }
 
@@ -38,10 +40,7 @@ public static MockWorld Create(Options options)
                     Vector3.zero)
                 .Result;
 
-            foreach (var type in options.AdditionalSystems ?? new Type[] { })
-            {
-                mockWorld.Worker.World.CreateSystem(type);
-            }
+            options.AdditionalSystems?.Invoke(mockWorld.Worker.World);
 
             mockWorld.Linker = new EntityGameObjectLinker(mockWorld.Worker.World);