diff --git a/src/js/game/belt_path.js b/src/js/game/belt_path.js
index 896b4ecd..99511d5a 100644
--- a/src/js/game/belt_path.js
+++ b/src/js/game/belt_path.js
@@ -1,14 +1,14 @@
 import { globalConfig } from "../core/config";
 import { DrawParameters } from "../core/draw_parameters";
-import { gItemRegistry } from "../core/global_registries";
 import { createLogger } from "../core/logging";
 import { Rectangle } from "../core/rectangle";
 import { epsilonCompare, round4Digits } from "../core/utils";
-import { enumDirection, enumDirectionToVector, Vector, enumInvertedDirections } from "../core/vector";
+import { enumDirection, enumDirectionToVector, enumInvertedDirections, Vector } from "../core/vector";
 import { BasicSerializableObject, types } from "../savegame/serialization";
 import { BaseItem } from "./base_item";
 import { Entity } from "./entity";
-import { GameRoot, enumLayer } from "./root";
+import { typeItemSingleton } from "./item_resolver";
+import { enumLayer, GameRoot } from "./root";
 
 const logger = createLogger("belt_path");
 
@@ -29,7 +29,7 @@ export class BeltPath extends BasicSerializableObject {
     static getSchema() {
         return {
             entityPath: types.array(types.entity),
-            items: types.array(types.pair(types.ufloat, types.obj(gItemRegistry))),
+            items: types.array(types.pair(types.ufloat, typeItemSingleton)),
             spacingToFirstItem: types.ufloat,
         };
     }
diff --git a/src/js/game/components/constant_signal.js b/src/js/game/components/constant_signal.js
index b2b37e44..b51277a1 100644
--- a/src/js/game/components/constant_signal.js
+++ b/src/js/game/components/constant_signal.js
@@ -2,6 +2,7 @@ import { gItemRegistry } from "../../core/global_registries";
 import { types } from "../../savegame/serialization";
 import { Component } from "../component";
 import { BaseItem } from "../base_item";
+import { typeItemSingleton } from "../item_resolver";
 
 export class ConstantSignalComponent extends Component {
     static getId() {
@@ -10,7 +11,7 @@ export class ConstantSignalComponent extends Component {
 
     static getSchema() {
         return {
-            signal: types.nullable(types.obj(gItemRegistry)),
+            signal: types.nullable(typeItemSingleton),
         };
     }
 
diff --git a/src/js/game/components/item_ejector.js b/src/js/game/components/item_ejector.js
index 281cf91e..b9a23c38 100644
--- a/src/js/game/components/item_ejector.js
+++ b/src/js/game/components/item_ejector.js
@@ -1,11 +1,10 @@
-import { Vector, enumDirection, enumDirectionToVector } from "../../core/vector";
-import { BaseItem } from "../base_item";
-import { Component } from "../component";
+import { enumDirection, enumDirectionToVector, Vector } from "../../core/vector";
 import { types } from "../../savegame/serialization";
-import { gItemRegistry } from "../../core/global_registries";
-import { Entity } from "../entity";
-import { enumLayer } from "../root";
+import { BaseItem } from "../base_item";
 import { BeltPath } from "../belt_path";
+import { Component } from "../component";
+import { Entity } from "../entity";
+import { typeItemSingleton } from "../item_resolver";
 
 /**
  * @typedef {{
@@ -29,7 +28,7 @@ export class ItemEjectorComponent extends Component {
         return {
             slots: types.array(
                 types.structured({
-                    item: types.nullable(types.obj(gItemRegistry)),
+                    item: types.nullable(typeItemSingleton),
                     progress: types.float,
                 })
             ),
diff --git a/src/js/game/components/item_processor.js b/src/js/game/components/item_processor.js
index 80617136..02b742d4 100644
--- a/src/js/game/components/item_processor.js
+++ b/src/js/game/components/item_processor.js
@@ -1,7 +1,7 @@
-import { gItemRegistry } from "../../core/global_registries";
 import { types } from "../../savegame/serialization";
 import { BaseItem } from "../base_item";
 import { Component } from "../component";
+import { typeItemSingleton } from "../item_resolver";
 
 /** @enum {string} */
 export const enumItemProcessorTypes = {
@@ -32,13 +32,13 @@ export class ItemProcessorComponent extends Component {
             nextOutputSlot: types.uint,
             inputSlots: types.array(
                 types.structured({
-                    item: types.obj(gItemRegistry),
+                    item: typeItemSingleton,
                     sourceSlot: types.uint,
                 })
             ),
             itemsToEject: types.array(
                 types.structured({
-                    item: types.obj(gItemRegistry),
+                    item: typeItemSingleton,
                     requiredSlot: types.nullable(types.uint),
                     preferredSlot: types.nullable(types.uint),
                 })
diff --git a/src/js/game/components/miner.js b/src/js/game/components/miner.js
index 411e49b9..a7515678 100644
--- a/src/js/game/components/miner.js
+++ b/src/js/game/components/miner.js
@@ -1,8 +1,7 @@
-import { globalConfig } from "../../core/config";
 import { types } from "../../savegame/serialization";
-import { Component } from "../component";
 import { BaseItem } from "../base_item";
-import { gItemRegistry } from "../../core/global_registries";
+import { Component } from "../component";
+import { typeItemSingleton } from "../item_resolver";
 
 const chainBufferSize = 3;
 
@@ -15,7 +14,7 @@ export class MinerComponent extends Component {
         // cachedMinedItem is not serialized.
         return {
             lastMiningTime: types.ufloat,
-            itemChainBuffer: types.array(types.obj(gItemRegistry)),
+            itemChainBuffer: types.array(typeItemSingleton),
         };
     }
 
diff --git a/src/js/game/components/storage.js b/src/js/game/components/storage.js
index acc68a51..a7fd365a 100644
--- a/src/js/game/components/storage.js
+++ b/src/js/game/components/storage.js
@@ -1,9 +1,7 @@
-import { Component } from "../component";
 import { types } from "../../savegame/serialization";
-import { gItemRegistry } from "../../core/global_registries";
 import { BaseItem, enumItemType } from "../base_item";
-import { ColorItem } from "../items/color_item";
-import { ShapeItem } from "../items/shape_item";
+import { Component } from "../component";
+import { typeItemSingleton } from "../item_resolver";
 
 export class StorageComponent extends Component {
     static getId() {
@@ -13,7 +11,7 @@ export class StorageComponent extends Component {
     static getSchema() {
         return {
             storedCount: types.uint,
-            storedItem: types.nullable(types.obj(gItemRegistry)),
+            storedItem: types.nullable(typeItemSingleton),
         };
     }
 
diff --git a/src/js/game/components/underground_belt.js b/src/js/game/components/underground_belt.js
index b09927ce..74351aac 100644
--- a/src/js/game/components/underground_belt.js
+++ b/src/js/game/components/underground_belt.js
@@ -1,10 +1,9 @@
-import { BaseItem } from "../base_item";
-import { Component } from "../component";
 import { globalConfig } from "../../core/config";
 import { types } from "../../savegame/serialization";
-import { gItemRegistry } from "../../core/global_registries";
+import { BaseItem } from "../base_item";
+import { Component } from "../component";
 import { Entity } from "../entity";
-import { enumLayer } from "../root";
+import { typeItemSingleton } from "../item_resolver";
 
 /** @enum {string} */
 export const enumUndergroundBeltMode = {
@@ -26,7 +25,7 @@ export class UndergroundBeltComponent extends Component {
 
     static getSchema() {
         return {
-            pendingItems: types.array(types.pair(types.obj(gItemRegistry), types.float)),
+            pendingItems: types.array(types.pair(typeItemSingleton, types.float)),
         };
     }
 
diff --git a/src/js/game/core.js b/src/js/game/core.js
index 12b97c71..7f28e638 100644
--- a/src/js/game/core.js
+++ b/src/js/game/core.js
@@ -13,7 +13,6 @@ import { randomInt, round2Digits } from "../core/utils";
 import { Vector } from "../core/vector";
 import { Savegame } from "../savegame/savegame";
 import { SavegameSerializer } from "../savegame/savegame_serializer";
-import { InGameState } from "../states/ingame";
 import { AutomaticSave } from "./automatic_save";
 import { MetaHubBuilding } from "./buildings/hub";
 import { Camera } from "./camera";
@@ -67,7 +66,7 @@ export class GameCore {
     /**
      * Initializes the root object which stores all game related data. The state
      * is required as a back reference (used sometimes)
-     * @param {InGameState} parentState
+     * @param {import("../states/ingame").InGameState} parentState
      * @param {Savegame} savegame
      */
     initializeRoot(parentState, savegame) {
diff --git a/src/js/game/item_resolver.js b/src/js/game/item_resolver.js
new file mode 100644
index 00000000..da15fa0c
--- /dev/null
+++ b/src/js/game/item_resolver.js
@@ -0,0 +1,33 @@
+import { types } from "../savegame/serialization";
+import { gItemRegistry } from "../core/global_registries";
+import { BooleanItem, BOOL_TRUE_SINGLETON, BOOL_FALSE_SINGLETON } from "./items/boolean_item";
+import { ShapeItem } from "./items/shape_item";
+import { ColorItem, COLOR_ITEM_SINGLETONS } from "./items/color_item";
+
+/**
+ * Resolves items so we share instances
+ * @param {import("../savegame/savegame_serializer").GameRoot} root
+ * @param {{$: string, data: any }} data
+ */
+export function itemResolverSingleton(root, data) {
+    const itemType = data.$;
+    const itemData = data.data;
+
+    switch (itemType) {
+        case BooleanItem.getId(): {
+            return itemData ? BOOL_TRUE_SINGLETON : BOOL_FALSE_SINGLETON;
+        }
+        case ShapeItem.getId(): {
+            return root.shapeDefinitionMgr.getShapeItemFromShortKey(itemData);
+        }
+        case ColorItem.getId(): {
+            return COLOR_ITEM_SINGLETONS[itemData];
+        }
+
+        default: {
+            assertAlways(false, "Unknown item type: " + itemType);
+        }
+    }
+}
+
+export const typeItemSingleton = types.obj(gItemRegistry, itemResolverSingleton);
diff --git a/src/js/game/items/color_item.js b/src/js/game/items/color_item.js
index 5cdcecaf..009b310b 100644
--- a/src/js/game/items/color_item.js
+++ b/src/js/game/items/color_item.js
@@ -98,3 +98,13 @@ export class ColorItem extends BaseItem {
         context.fill();
     }
 }
+
+/**
+ * Singleton instances
+ * @type {Object<enumColors, ColorItem>}
+ */
+export const COLOR_ITEM_SINGLETONS = {};
+
+for (const color in enumColors) {
+    COLOR_ITEM_SINGLETONS[color] = new ColorItem(color);
+}
diff --git a/src/js/game/items/shape_item.js b/src/js/game/items/shape_item.js
index 8ebf1d34..44a0a3ad 100644
--- a/src/js/game/items/shape_item.js
+++ b/src/js/game/items/shape_item.js
@@ -37,7 +37,6 @@ export class ShapeItem extends BaseItem {
      */
     constructor(definition) {
         super();
-        // logger.log("New shape item for shape definition", definition.generateId(), "created");
 
         /**
          * This property must not be modified on runtime, you have to clone the class in order to change the definition
diff --git a/src/js/game/map_chunk.js b/src/js/game/map_chunk.js
index 138f423f..189a62cd 100644
--- a/src/js/game/map_chunk.js
+++ b/src/js/game/map_chunk.js
@@ -6,7 +6,7 @@ import { Vector } from "../core/vector";
 import { BaseItem } from "./base_item";
 import { enumColors } from "./colors";
 import { Entity } from "./entity";
-import { ColorItem } from "./items/color_item";
+import { COLOR_ITEM_SINGLETONS } from "./items/color_item";
 import { enumLayer, GameRoot } from "./root";
 import { enumSubShape } from "./shape_definition";
 
@@ -139,7 +139,7 @@ export class MapChunk {
         if (distanceToOriginInChunks > 2) {
             availableColors.push(enumColors.blue);
         }
-        this.internalGeneratePatch(rng, colorPatchSize, new ColorItem(rng.choice(availableColors)));
+        this.internalGeneratePatch(rng, colorPatchSize, COLOR_ITEM_SINGLETONS[rng.choice(availableColors)]);
     }
 
     /**
@@ -268,7 +268,7 @@ export class MapChunk {
      */
     generatePredefined(rng) {
         if (this.x === 0 && this.y === 0) {
-            this.internalGeneratePatch(rng, 2, new ColorItem(enumColors.red), 7, 7);
+            this.internalGeneratePatch(rng, 2, COLOR_ITEM_SINGLETONS[enumColors.red], 7, 7);
             return true;
         }
         if (this.x === -1 && this.y === 0) {
@@ -283,7 +283,7 @@ export class MapChunk {
         }
 
         if (this.x === -1 && this.y === -1) {
-            this.internalGeneratePatch(rng, 2, new ColorItem(enumColors.green));
+            this.internalGeneratePatch(rng, 2, COLOR_ITEM_SINGLETONS[enumColors.green]);
             return true;
         }
 
diff --git a/src/js/game/systems/constant_signal.js b/src/js/game/systems/constant_signal.js
index e0c67e9e..f1ea9f48 100644
--- a/src/js/game/systems/constant_signal.js
+++ b/src/js/game/systems/constant_signal.js
@@ -1,15 +1,14 @@
-import { ConstantSignalComponent } from "../components/constant_signal";
-import { GameSystemWithFilter } from "../game_system_with_filter";
-import { Entity } from "../entity";
+import trim from "trim";
 import { DialogWithForm } from "../../core/modal_dialog_elements";
 import { FormElementInput } from "../../core/modal_dialog_forms";
-import { enumColors } from "../colors";
-import { ColorItem } from "../items/color_item";
-import trim from "trim";
-import { BOOL_TRUE_SINGLETON, BOOL_FALSE_SINGLETON } from "../items/boolean_item";
-import { ShapeDefinition } from "../shape_definition";
-import { ShapeItem } from "../items/shape_item";
 import { BaseItem } from "../base_item";
+import { enumColors } from "../colors";
+import { ConstantSignalComponent } from "../components/constant_signal";
+import { Entity } from "../entity";
+import { GameSystemWithFilter } from "../game_system_with_filter";
+import { BOOL_FALSE_SINGLETON, BOOL_TRUE_SINGLETON } from "../items/boolean_item";
+import { COLOR_ITEM_SINGLETONS } from "../items/color_item";
+import { ShapeDefinition } from "../shape_definition";
 
 export class ConstantSignalSystem extends GameSystemWithFilter {
     constructor(root) {
@@ -111,7 +110,7 @@ export class ConstantSignalSystem extends GameSystemWithFilter {
         const codeLower = code.toLowerCase();
 
         if (enumColors[codeLower]) {
-            return new ColorItem(codeLower);
+            return COLOR_ITEM_SINGLETONS[codeLower];
         }
         if (code === "1" || codeLower === "true") {
             return BOOL_TRUE_SINGLETON;
@@ -122,7 +121,7 @@ export class ConstantSignalSystem extends GameSystemWithFilter {
         }
 
         if (ShapeDefinition.isValidShortKey(code)) {
-            return new ShapeItem(this.root.shapeDefinitionMgr.getShapeFromShortKey(code));
+            return this.root.shapeDefinitionMgr.getShapeItemFromShortKey(code);
         }
 
         return null;
diff --git a/src/js/game/systems/hub.js b/src/js/game/systems/hub.js
index dafdb498..b8968655 100644
--- a/src/js/game/systems/hub.js
+++ b/src/js/game/systems/hub.js
@@ -1,11 +1,10 @@
-import { GameSystemWithFilter } from "../game_system_with_filter";
-import { HubComponent } from "../components/hub";
 import { DrawParameters } from "../../core/draw_parameters";
-import { Entity } from "../entity";
-import { formatBigNumber } from "../../core/utils";
 import { Loader } from "../../core/loader";
+import { formatBigNumber } from "../../core/utils";
 import { T } from "../../translations";
-import { ShapeItem } from "../items/shape_item";
+import { HubComponent } from "../components/hub";
+import { Entity } from "../entity";
+import { GameSystemWithFilter } from "../game_system_with_filter";
 
 export class HubSystem extends GameSystemWithFilter {
     constructor(root) {
@@ -23,7 +22,9 @@ export class HubSystem extends GameSystemWithFilter {
             // Set hub goal
             const entity = this.allEntities[i];
             const pinsComp = entity.components.WiredPins;
-            pinsComp.slots[0].value = new ShapeItem(this.root.hubGoals.currentGoal.definition);
+            pinsComp.slots[0].value = this.root.shapeDefinitionMgr.getShapeItemFromDefinition(
+                this.root.hubGoals.currentGoal.definition
+            );
         }
     }
 
diff --git a/src/js/game/systems/item_processor.js b/src/js/game/systems/item_processor.js
index ad4a7ae8..9943594c 100644
--- a/src/js/game/systems/item_processor.js
+++ b/src/js/game/systems/item_processor.js
@@ -5,7 +5,7 @@ import { enumItemProcessorTypes, ItemProcessorComponent } from "../components/it
 import { Entity } from "../entity";
 import { GameSystemWithFilter } from "../game_system_with_filter";
 import { BOOL_TRUE_SINGLETON } from "../items/boolean_item";
-import { ColorItem } from "../items/color_item";
+import { ColorItem, COLOR_ITEM_SINGLETONS } from "../items/color_item";
 import { ShapeItem } from "../items/shape_item";
 
 export class ItemProcessorSystem extends GameSystemWithFilter {
@@ -134,7 +134,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
                     const definition = cutDefinitions[i];
                     if (!definition.isEntirelyEmpty()) {
                         outItems.push({
-                            item: new ShapeItem(definition),
+                            item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(definition),
                             requiredSlot: i,
                         });
                     }
@@ -155,7 +155,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
                     const definition = cutDefinitions[i];
                     if (!definition.isEntirelyEmpty()) {
                         outItems.push({
-                            item: new ShapeItem(definition),
+                            item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(definition),
                             requiredSlot: i,
                         });
                     }
@@ -172,7 +172,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
 
                 const rotatedDefinition = this.root.shapeDefinitionMgr.shapeActionRotateCW(inputDefinition);
                 outItems.push({
-                    item: new ShapeItem(rotatedDefinition),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(rotatedDefinition),
                 });
                 break;
             }
@@ -185,7 +185,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
 
                 const rotatedDefinition = this.root.shapeDefinitionMgr.shapeActionRotateCCW(inputDefinition);
                 outItems.push({
-                    item: new ShapeItem(rotatedDefinition),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(rotatedDefinition),
                 });
                 break;
             }
@@ -198,7 +198,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
 
                 const rotatedDefinition = this.root.shapeDefinitionMgr.shapeActionRotateFL(inputDefinition);
                 outItems.push({
-                    item: new ShapeItem(rotatedDefinition),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(rotatedDefinition),
                 });
                 break;
             }
@@ -217,7 +217,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
                     upperItem.definition
                 );
                 outItems.push({
-                    item: new ShapeItem(stackedDefinition),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(stackedDefinition),
                 });
                 break;
             }
@@ -248,7 +248,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
                     resultColor = mixedColor;
                 }
                 outItems.push({
-                    item: new ColorItem(resultColor),
+                    item: COLOR_ITEM_SINGLETONS[resultColor],
                 });
 
                 break;
@@ -266,7 +266,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
                 );
 
                 outItems.push({
-                    item: new ShapeItem(colorizedDefinition),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(colorizedDefinition),
                 });
 
                 break;
@@ -293,11 +293,11 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
                     colorItem.color
                 );
                 outItems.push({
-                    item: new ShapeItem(colorizedDefinition1),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(colorizedDefinition1),
                 });
 
                 outItems.push({
-                    item: new ShapeItem(colorizedDefinition2),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(colorizedDefinition2),
                 });
 
                 break;
@@ -324,7 +324,7 @@ export class ItemProcessorSystem extends GameSystemWithFilter {
                 );
 
                 outItems.push({
-                    item: new ShapeItem(colorizedDefinition),
+                    item: this.root.shapeDefinitionMgr.getShapeItemFromDefinition(colorizedDefinition),
                 });
 
                 break;
diff --git a/src/js/savegame/serialization.js b/src/js/savegame/serialization.js
index aea2f944..9f998a0f 100644
--- a/src/js/savegame/serialization.js
+++ b/src/js/savegame/serialization.js
@@ -1,8 +1,11 @@
+import { createLogger } from "../core/logging";
 import {
     BaseDataType,
     TypeArray,
     TypeBoolean,
     TypeClass,
+    TypeClassData,
+    TypeClassFromMetaclass,
     TypeClassId,
     TypeEntity,
     TypeEntityWeakref,
@@ -17,12 +20,9 @@ import {
     TypePositiveInteger,
     TypePositiveNumber,
     TypeString,
-    TypeVector,
-    TypeClassFromMetaclass,
-    TypeClassData,
     TypeStructuredObject,
+    TypeVector,
 } from "./serialization_data_types";
-import { createLogger } from "../core/logging";
 
 const logger = createLogger("serialization");
 
@@ -69,9 +69,10 @@ export const types = {
 
     /**
      * @param {FactoryTemplate<*>} registry
+     * @param {(GameRoot, any) => object=} resolver
      */
-    obj(registry) {
-        return new TypeClass(registry);
+    obj(registry, resolver = null) {
+        return new TypeClass(registry, resolver);
     },
 
     /**
@@ -190,12 +191,18 @@ export class BasicSerializableObject {
         );
     }
 
-    /** @returns {string|void} */
-    deserialize(data) {
+    /**
+     * @param {any} data
+     * @param {import("./savegame_serializer").GameRoot} root
+     * @returns {string|void}
+     */
+    deserialize(data, root = null) {
         return deserializeSchema(
             this,
             /** @type {typeof BasicSerializableObject} */ (this.constructor).getCachedSchema(),
-            data
+            data,
+            null,
+            root
         );
     }
 
@@ -253,9 +260,10 @@ export function serializeSchema(obj, schema, mergeWith = {}) {
  * @param {Schema} schema The schema to use
  * @param {object} data The serialized data
  * @param {string|void|null=} baseclassErrorResult Convenience, if this is a string error code, do nothing and return it
+ * @param {import("../game/root").GameRoot=} root Optional game root reference
  * @returns {string|void} String error code or nothing on success
  */
-export function deserializeSchema(obj, schema, data, baseclassErrorResult = null) {
+export function deserializeSchema(obj, schema, data, baseclassErrorResult = null, root) {
     if (baseclassErrorResult) {
         return baseclassErrorResult;
     }
@@ -275,7 +283,7 @@ export function deserializeSchema(obj, schema, data, baseclassErrorResult = null
             return "Non-nullable entry is null: " + key + " of class " + obj.constructor.name;
         }
 
-        const errorStatus = schema[key].deserializeWithVerify(data[key], obj, key, obj.root);
+        const errorStatus = schema[key].deserializeWithVerify(data[key], obj, key, obj.root || root);
         if (errorStatus) {
             logger.error(
                 "Deserialization failed with error '" + errorStatus + "' on object",
diff --git a/src/js/savegame/serialization_data_types.js b/src/js/savegame/serialization_data_types.js
index c9ab570d..033acda1 100644
--- a/src/js/savegame/serialization_data_types.js
+++ b/src/js/savegame/serialization_data_types.js
@@ -595,10 +595,12 @@ export class TypeClass extends BaseDataType {
     /**
      *
      * @param {FactoryTemplate<*>} registry
+     * @param {(GameRoot, object) => object} customResolver
      */
-    constructor(registry) {
+    constructor(registry, customResolver = null) {
         super();
         this.registry = registry;
+        this.customResolver = customResolver;
     }
 
     serialize(value) {
@@ -640,14 +642,23 @@ export class TypeClass extends BaseDataType {
      * @returns {string|void} String error code or null on success
      */
     deserialize(value, targetObject, targetKey, root) {
-        const instanceClass = this.registry.findById(value.$);
-        if (!instanceClass || !instanceClass.prototype) {
-            return "Invalid class id (runtime-err): " + value.$ + "->" + instanceClass;
-        }
-        const instance = Object.create(instanceClass.prototype);
-        const errorState = instance.deserialize(value.data);
-        if (errorState) {
-            return errorState;
+        let instance;
+
+        if (this.customResolver) {
+            instance = this.customResolver(root, value);
+            if (!instance) {
+                return "Failed to call custom resolver";
+            }
+        } else {
+            const instanceClass = this.registry.findById(value.$);
+            if (!instanceClass || !instanceClass.prototype) {
+                return "Invalid class id (runtime-err): " + value.$ + "->" + instanceClass;
+            }
+            instance = Object.create(instanceClass.prototype);
+            const errorState = instance.deserialize(value.data);
+            if (errorState) {
+                return errorState;
+            }
         }
         targetObject[targetKey] = instance;
     }
diff --git a/src/js/savegame/serializer_internal.js b/src/js/savegame/serializer_internal.js
index 5d0c3bfc..ee32dff6 100644
--- a/src/js/savegame/serializer_internal.js
+++ b/src/js/savegame/serializer_internal.js
@@ -60,7 +60,7 @@ export class SerializerInternal {
 
         entity.uid = payload.uid;
 
-        this.deserializeComponents(entity, payload.components);
+        this.deserializeComponents(root, entity, payload.components);
 
         root.entityMgr.registerEntity(entity, payload.uid);
         root.map.placeStaticEntity(entity);
@@ -70,18 +70,19 @@ export class SerializerInternal {
 
     /**
      * Deserializes components of an entity
+     * @param {GameRoot} root
      * @param {Entity} entity
      * @param {Object.<string, any>} data
      * @returns {string|void}
      */
-    deserializeComponents(entity, data) {
+    deserializeComponents(root, entity, data) {
         for (const componentId in data) {
             if (!entity.components[componentId]) {
                 logger.warn("Entity no longer has component:", componentId);
                 continue;
             }
 
-            const errorStatus = entity.components[componentId].deserialize(data[componentId]);
+            const errorStatus = entity.components[componentId].deserialize(data[componentId], root);
             if (errorStatus) {
                 return errorStatus;
             }