diff --git a/scenes/player.tscn b/scenes/player.tscn
index 1e98353..64f0831 100644
--- a/scenes/player.tscn
+++ b/scenes/player.tscn
@@ -62,6 +62,10 @@ advance_mode = 2
 advance_mode = 2
 advance_expression = "is_aiming()"
 
+[sub_resource type="AnimationNodeStateMachineTransition" id="AnimationNodeStateMachineTransition_qfm1y"]
+advance_mode = 2
+advance_expression = "not is_aiming()"
+
 [sub_resource type="AnimationNodeStateMachineTransition" id="AnimationNodeStateMachineTransition_oprun"]
 advance_mode = 2
 advance_expression = "is_firing()"
@@ -70,18 +74,14 @@ advance_expression = "is_firing()"
 switch_mode = 2
 advance_mode = 2
 
-[sub_resource type="AnimationNodeStateMachineTransition" id="AnimationNodeStateMachineTransition_qfm1y"]
-advance_mode = 2
-advance_expression = "not is_aiming()"
-
 [sub_resource type="AnimationNodeStateMachine" id="AnimationNodeStateMachine_3v2ag"]
 states/Aim/node = SubResource("AnimationNodeAnimation_d2wvv")
 states/Aim/position = Vector2(551, 100)
 states/Fire/node = SubResource("AnimationNodeAnimation_3v2ag")
-states/Fire/position = Vector2(687, 100)
+states/Fire/position = Vector2(730, 100)
 states/Movement/node = SubResource("AnimationNodeBlendTree_d2wvv")
 states/Movement/position = Vector2(403, 100)
-transitions = ["Start", "Movement", SubResource("AnimationNodeStateMachineTransition_jej6c"), "Movement", "Aim", SubResource("AnimationNodeStateMachineTransition_f1ej7"), "Aim", "Fire", SubResource("AnimationNodeStateMachineTransition_oprun"), "Fire", "Aim", SubResource("AnimationNodeStateMachineTransition_a8ls1"), "Aim", "Movement", SubResource("AnimationNodeStateMachineTransition_qfm1y")]
+transitions = ["Start", "Movement", SubResource("AnimationNodeStateMachineTransition_jej6c"), "Movement", "Aim", SubResource("AnimationNodeStateMachineTransition_f1ej7"), "Aim", "Movement", SubResource("AnimationNodeStateMachineTransition_qfm1y"), "Aim", "Fire", SubResource("AnimationNodeStateMachineTransition_oprun"), "Fire", "Aim", SubResource("AnimationNodeStateMachineTransition_a8ls1")]
 
 [sub_resource type="AnimationNodeAnimation" id="AnimationNodeAnimation_sk752"]
 animation = &"Idle"
@@ -162,7 +162,7 @@ tree_root = SubResource("AnimationNodeStateMachine_5lvsk")
 advance_expression_base_node = NodePath("..")
 anim_player = NodePath("../Mesh/AnimationPlayer")
 parameters/Handgun/Movement/Blend2/blend_amount = 1.0
-parameters/Handgun/Movement/BlendSpace1D/blend_position = 0.229277
+parameters/Handgun/Movement/BlendSpace1D/blend_position = 0.5
 parameters/Unarmed/blend_position = 0.872134
 script = ExtResource("3_26yay")
 move_speed_expression = "move_speed()"
diff --git a/src/async_resource_handler.ts b/src/async_resource_handler.ts
new file mode 100644
index 0000000..569b6c2
--- /dev/null
+++ b/src/async_resource_handler.ts
@@ -0,0 +1,73 @@
+import { GArray, GError, Node, Resource, ResourceLoader, ResourceSaver } from 'godot'
+import { GodotError } from './godot_error'
+
+export class ResourceLoadError extends Error { }
+
+export default class AsyncResourceHandler extends Node {
+  private static _instance: AsyncResourceHandler
+  static readonly SaveFlags = ResourceSaver.SaverFlags
+  static readonly CacheMode = ResourceLoader.CacheMode
+
+  static get instance() {
+    return this._instance
+  }
+
+  _ready(): void {
+    AsyncResourceHandler._instance = this
+  }
+
+  static save<T extends Resource>(path: string, data: T, flags: ResourceSaver.SaverFlags): Promise<void> {
+    return this._instance.save(path, data, flags)
+  }
+
+  save<T extends Resource>(path: string, data: T, flags: ResourceSaver.SaverFlags): Promise<void> {
+    return new Promise((resolve, reject) => {
+      const err = ResourceSaver.save(data, path, flags)
+
+      if (err === GError.OK) {
+        resolve()
+      } else {
+        reject(err)
+      }
+    })
+  }
+
+  static load<T extends Resource>(path: string, hint_string: string = '', use_sub_threads?: boolean, cache_mode?: ResourceLoader.CacheMode): Promise<T> {
+    return this._instance.load(path, hint_string, use_sub_threads, cache_mode)
+  }
+
+  load<T extends Resource>(path: string, hint_string: string = '', use_sub_threads?: boolean, cache_mode?: ResourceLoader.CacheMode): Promise<T> {
+    return new Promise(async (resolve, reject) => {
+      const err = ResourceLoader.load_threaded_request(path, hint_string, use_sub_threads, cache_mode)
+
+      if (err != GError.OK) {
+        return reject(new GodotError(err))
+      }
+
+      const get_status = () => ResourceLoader.load_threaded_get_status(path)
+
+      let status = get_status()
+      while (status === ResourceLoader.ThreadLoadStatus.THREAD_LOAD_IN_PROGRESS) {
+        await this.get_tree().process_frame.as_promise()
+        status = get_status()
+      }
+
+      if (status === ResourceLoader.ThreadLoadStatus.THREAD_LOAD_LOADED) {
+        return resolve(ResourceLoader.load_threaded_get(path) as T)
+      } else {
+        return reject(new ResourceLoadError())
+      }
+    })
+  }
+
+  static get_progress(path: string): number {
+    return this._instance.get_progress(path)
+  }
+
+  get_progress(path: string): number {
+    const arr = new GArray()
+    ResourceLoader.load_threaded_get_status(path, arr)
+    return arr.get_indexed(0)
+  }
+}
+
diff --git a/src/async_resource_handler.ts.uid b/src/async_resource_handler.ts.uid
new file mode 100644
index 0000000..a387ea8
--- /dev/null
+++ b/src/async_resource_handler.ts.uid
@@ -0,0 +1 @@
+uid://byri2tpbtahpd
diff --git a/src/async_resource_loader.ts b/src/async_resource_loader.ts
index 1b521af..329d7db 100644
--- a/src/async_resource_loader.ts
+++ b/src/async_resource_loader.ts
@@ -1,22 +1,39 @@
-import { GError, Node, Resource, ResourceLoader } from 'godot'
+import { GArray, GError, Node, Resource, ResourceLoader, ResourceSaver } from 'godot'
+import { GodotError } from './godot_error'
 
-export default class AsyncResourceLoader extends Node {
-  private static _instance: AsyncResourceLoader
+export class ResourceLoadError extends Error { }
+
+export default class AsyncResourceHandler extends Node {
+  private static _instance: AsyncResourceHandler
+  static readonly SaveFlags = ResourceSaver.SaverFlags
+  static readonly CacheMode = ResourceLoader.CacheMode
 
   static get instance() {
     return this._instance
   }
 
   _ready(): void {
-    AsyncResourceLoader._instance = this
+    AsyncResourceHandler._instance = this
   }
 
-  load<T extends Resource>(path: string, hint_string: string = ''): Promise<T> {
+  save<T extends Resource>(path: string, data: T, flags: ResourceSaver.SaverFlags): Promise<void> {
+    return new Promise((resolve, reject) => {
+      const err = ResourceSaver.save(data, path, flags)
+
+      if (err === GError.OK) {
+        resolve()
+      } else {
+        reject(err)
+      }
+    })
+  }
+
+  load<T extends Resource>(path: string, hint_string: string = '', use_sub_threads?: boolean, cache_mode?: ResourceLoader.CacheMode): Promise<T> {
     return new Promise(async (resolve, reject) => {
-      const err = ResourceLoader.load_threaded_request(path, hint_string)
+      const err = ResourceLoader.load_threaded_request(path, hint_string, use_sub_threads, cache_mode)
 
       if (err != GError.OK) {
-        return reject(new Error(`failed to load ${path}`))
+        return reject(new GodotError(err))
       }
 
       const get_status = () => ResourceLoader.load_threaded_get_status(path)
@@ -27,12 +44,18 @@ export default class AsyncResourceLoader extends Node {
         status = get_status()
       }
 
-      if (get_status() === ResourceLoader.ThreadLoadStatus.THREAD_LOAD_LOADED) {
+      if (status === ResourceLoader.ThreadLoadStatus.THREAD_LOAD_LOADED) {
         return resolve(ResourceLoader.load_threaded_get(path) as T)
       } else {
-        return reject(new Error(`failed to load ${path}`))
+        return reject(new ResourceLoadError())
       }
     })
   }
+
+  get_progress(path: string): number {
+    const arr = new GArray()
+    ResourceLoader.load_threaded_get_status(path, arr)
+    return arr.get_indexed(0)
+  }
 }
 
diff --git a/src/equipped_weapon.ts b/src/equipped_weapon.ts
index 3804c73..4c459b9 100644
--- a/src/equipped_weapon.ts
+++ b/src/equipped_weapon.ts
@@ -2,10 +2,10 @@ import { Color, GArray, Node, Node3D, PackedScene, PhysicsBody3D, PhysicsRayQuer
 import { export_file, signal } from 'godot.annotations'
 import { export_node, onready } from './annotations'
 import Weapon from './weapon'
-import AsyncResourceLoader from './async_resource_loader'
+import AsyncResourceHandler from './async_resource_handler'
 import { forward } from './vec'
 import DebugDraw from './debug_draw'
-import { find_in_anscestors, find_in_descendents, implements_interface } from './node'
+import { find_in_anscestors, find_in_descendents, has_method } from './node'
 import { Damageable } from './health'
 
 const { MULTIPLY: mul, ADD: add } = Vector3
@@ -36,7 +36,7 @@ export default class EquippedWeapon extends Node3D {
 
   _ready(): void {
     if (this.starting_weapon != null) {
-      AsyncResourceLoader.instance.load<Weapon>(this.starting_weapon, 'Weapon').then(weapon => this.equip(weapon))
+      AsyncResourceHandler.instance.load<Weapon>(this.starting_weapon, 'Weapon').then(weapon => this.equip(weapon))
     }
   }
 
@@ -61,7 +61,7 @@ export default class EquippedWeapon extends Node3D {
   }
 
   equip(weapon: Weapon) {
-    AsyncResourceLoader.instance.load<PackedScene>(weapon.scene, 'PackedScene')
+    AsyncResourceHandler.instance.load<PackedScene>(weapon.scene, 'PackedScene')
       .then(scene => this._parent_scene_to_transform(scene))
 
     if (this._has_equipped_weapon) {
@@ -86,7 +86,7 @@ export default class EquippedWeapon extends Node3D {
       if (!result.is_empty()) {
         DebugDraw.draw_ray(query, Color.DARK_RED)
         const root = find_in_anscestors(result.get('collider'), n => n instanceof PhysicsBody3D)
-        const health = find_in_descendents<Node & Damageable>(root, n => implements_interface<Damageable>(['apply_damage'], n))
+        const health = find_in_descendents<Node & Damageable>(root, n => has_method('apply_damage', n))
         if (health != null) {
           health.apply_damage(this, this._equipped_weapon.damage)
         }
diff --git a/src/godot_error.ts b/src/godot_error.ts
new file mode 100644
index 0000000..d11fe1e
--- /dev/null
+++ b/src/godot_error.ts
@@ -0,0 +1,12 @@
+import { GError } from "godot";
+
+export class GodotError extends Error {
+  error: GError
+
+  constructor(err: GError, message?: string) {
+    super(message || `Godot error (${err})`)
+    this.error = err
+  }
+
+}
+
diff --git a/src/godot_error.ts.uid b/src/godot_error.ts.uid
new file mode 100644
index 0000000..1c8d671
--- /dev/null
+++ b/src/godot_error.ts.uid
@@ -0,0 +1 @@
+uid://o3gcj3wh78yt
diff --git a/src/node.ts b/src/node.ts
index c6409f4..aa500bb 100644
--- a/src/node.ts
+++ b/src/node.ts
@@ -11,8 +11,14 @@ export function queue_free_children<T extends Node>(node: T) {
   }
 }
 
+type RequiredField<T, Field extends keyof T> = Omit<T, Field> & Required<Pick<T, Field>>
+
+export function has_method(name: StringName, obj: Object): boolean {
+  return obj.has_method(name)
+}
+
 export function implements_interface<T>(method_names: StringName[], obj: Object): obj is Object & T {
-  return method_names.every(name => obj.has_method(name))
+  return method_names.every(name => has_method(name, obj))
 }
 
 export function find_in_anscestors<T extends Node>(root: T | null | undefined, predicate: Predicate<Node>, height: number = Infinity): T | null | undefined {
diff --git a/src/node.ts.uid b/src/node.ts.uid
new file mode 100644
index 0000000..6b0b660
--- /dev/null
+++ b/src/node.ts.uid
@@ -0,0 +1 @@
+uid://d0npi365fttf6
diff --git a/src/save_serializer.ts b/src/save_serializer.ts
new file mode 100644
index 0000000..4608478
--- /dev/null
+++ b/src/save_serializer.ts
@@ -0,0 +1,87 @@
+import { GDictionary, Node, PackedScene, Resource, ResourceLoader, ResourceSaver } from 'godot'
+import AsyncResourceHandler from './async_resource_handler'
+import { has_method } from './node'
+
+interface Serializable {
+  on_save_game(save_data: GameState): void
+  on_before_load_game?(): void
+  on_load_game<T extends SaveState>(state: T): void
+}
+
+interface SaveState extends Resource {
+  scene: string
+}
+
+class PlayerState extends Resource implements SaveState {
+  condition: undefined = undefined
+  inventory: undefined = undefined
+  scene: string = ''
+}
+
+class ProgressState extends Resource {
+  variables?: GDictionary
+}
+
+export class GameState extends Resource {
+  player?: PlayerState
+  progress?: ProgressState
+  world?: SaveState[]
+}
+
+const StateMethod = {
+  Save: 'on_save_game',
+  BeforeLoad: 'on_before_load_game',
+  Load: 'on_load_game'
+} as const
+
+type StateMethod = typeof StateMethod[keyof typeof StateMethod]
+
+export default class SaveSerializer extends Node {
+  private static _save_group: string = 'save'
+
+  private static _instance: SaveSerializer
+
+  _ready() {
+    SaveSerializer._instance = this
+  }
+
+  static save() {
+    this._instance.save()
+  }
+
+  private _announce(method: StateMethod, ...args: any) {
+    this.get_tree().call_group(
+      SaveSerializer._save_group,
+      method,
+      ...args
+    )
+  }
+
+  save() {
+    const game_state: GameState = new GameState()
+
+    this._announce(StateMethod.Save, game_state)
+
+    ResourceSaver.save(game_state, 'user://save1.tres')
+  }
+
+  private async _restore_node<T extends SaveState>(state: T, parent: Node) {
+    const scene: PackedScene = await AsyncResourceHandler.load(state.scene, 'PackedScene')
+    const node = scene.instantiate()
+    parent.add_child(node)
+
+    if (has_method(StateMethod.Load, node)) {
+      // TODO: type check for state method
+    }
+
+  }
+
+  async load() {
+    const loaded_state: GameState = await AsyncResourceHandler.load('user://save1.tres')
+    this._announce(StateMethod.BeforeLoad)
+    // TODO: pass world root as 2nd param
+    const node_promises = loaded_state.world?.map(state => this._restore_node(state, this)) ?? []
+    return Promise.all(node_promises)
+  }
+}
+
diff --git a/src/save_serializer.ts.uid b/src/save_serializer.ts.uid
new file mode 100644
index 0000000..3424e91
--- /dev/null
+++ b/src/save_serializer.ts.uid
@@ -0,0 +1 @@
+uid://xv4ix5esb3ij