diff --git a/Source/Engine/Actor.swift b/Source/Engine/Actor.swift
index bdff51b..e9b32f4 100644
--- a/Source/Engine/Actor.swift
+++ b/Source/Engine/Actor.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public protocol Actor {
+public protocol Actor: Codable {
     var radius: Double { get }
     var position: Vector { get set }
 }
diff --git a/Source/Engine/Animation.swift b/Source/Engine/Animation.swift
index a22301e..409bd23 100644
--- a/Source/Engine/Animation.swift
+++ b/Source/Engine/Animation.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public struct Animation {
+public struct Animation: Codable {
     public let frames: [Texture]
     public let duration: Double
     public var time: Double = 0
diff --git a/Source/Engine/Monster.swift b/Source/Engine/Monster.swift
index 201c867..285d754 100644
--- a/Source/Engine/Monster.swift
+++ b/Source/Engine/Monster.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public enum MonsterState {
+public enum MonsterState: Int, Codable {
     case idle
     case chasing
     case scratching
diff --git a/Source/Engine/Textures.swift b/Source/Engine/Textures.swift
index 1088d84..dd61ee8 100644
--- a/Source/Engine/Textures.swift
+++ b/Source/Engine/Textures.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public enum Texture: String, CaseIterable {
+public enum Texture: String, CaseIterable, Codable {
     case wall, wall2
     case crackWall, crackWall2
     case slimeWall, slimeWall2
diff --git a/Source/Engine/Thing.swift b/Source/Engine/Thing.swift
index 786b7c4..1d5d9b7 100644
--- a/Source/Engine/Thing.swift
+++ b/Source/Engine/Thing.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public enum Thing: Int, Decodable {
+public enum Thing: Int, Codable {
     case nothing
     case player
     case monster
diff --git a/Source/Engine/Tile.swift b/Source/Engine/Tile.swift
index 1e9b15b..3e48846 100644
--- a/Source/Engine/Tile.swift
+++ b/Source/Engine/Tile.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public enum Tile: Int, Decodable {
+public enum Tile: Int, Codable {
     case floor
     case wall
     case crackWall
diff --git a/Source/Engine/Tilemap.swift b/Source/Engine/Tilemap.swift
index aa26d59..27121cd 100644
--- a/Source/Engine/Tilemap.swift
+++ b/Source/Engine/Tilemap.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public struct Tilemap: Decodable {
+public struct Tilemap: Codable {
     private let tiles: [Tile]
     public let things: [Thing]
     public let width: Int
diff --git a/Source/Engine/Vector.swift b/Source/Engine/Vector.swift
index 40ac090..3b3d0bb 100644
--- a/Source/Engine/Vector.swift
+++ b/Source/Engine/Vector.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public struct Vector {
+public struct Vector: Codable {
     public var x, y: Double
 
     public init(x: Double, y: Double) {
diff --git a/Source/Engine/World.swift b/Source/Engine/World.swift
index 708d7d7..c4ad36b 100644
--- a/Source/Engine/World.swift
+++ b/Source/Engine/World.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public struct World {
+public struct World: Codable {
     public let map: Tilemap
     public var monsters: [Monster]
     public var player: Player!
diff --git a/Source/Rampage.xcodeproj/project.pbxproj b/Source/Rampage.xcodeproj/project.pbxproj
index 8b3497f..e4c4390 100644
--- a/Source/Rampage.xcodeproj/project.pbxproj
+++ b/Source/Rampage.xcodeproj/project.pbxproj
@@ -152,6 +152,7 @@
 				012A0C6022CC200D0068E8EF /* Billboard.swift */,
 				01D09AF222A482030052745A /* Bitmap.swift */,
 				01D09AF022A481AB0052745A /* Color.swift */,
+				01D09B0E22AA49D40052745A /* Game.swift */,
 				01D09B0222A4958E0052745A /* Input.swift */,
 				012A0C6122CC200D0068E8EF /* Monster.swift */,
 				01D09AFA22A485040052745A /* Player.swift */,
@@ -297,6 +298,7 @@
 				012A0C6322CC200E0068E8EF /* Monster.swift in Sources */,
 				01D09B0B22A7F7570052745A /* Textures.swift in Sources */,
 				01D09AFF22A48E990052745A /* Tilemap.swift in Sources */,
+				01D09B0F22AA49D40052745A /* Game.swift in Sources */,
 				01D09AFD22A4873B0052745A /* Rect.swift in Sources */,
 				01ADC63C22B957FD00DC8AAD /* Renderer.swift in Sources */,
 				012A0C9E22D47C220068E8EF /* Actor.swift in Sources */,
diff --git a/Source/Rampage/ViewController.swift b/Source/Rampage/ViewController.swift
index dee112e..6e8101a 100644
--- a/Source/Rampage/ViewController.swift
+++ b/Source/Rampage/ViewController.swift
@@ -12,6 +12,7 @@ import Engine
 private let joystickRadius: Double = 40
 private let maximumTimeStep: Double = 1 / 20
 private let worldTimeStep: Double = 1 / 120
+private let savePath = "~/Documents/quicksave.json"
 
 private func loadMap() -> Tilemap {
     let jsonURL = Bundle.main.url(forResource: "Map", withExtension: "json")!
@@ -40,6 +41,15 @@ class ViewController: UIViewController {
         displayLink.add(to: .main, forMode: .common)
 
         view.addGestureRecognizer(panGesture)
+
+        try? restoreState()
+        NotificationCenter.default.addObserver(
+            forName: UIApplication.willResignActiveNotification,
+            object: nil,
+            queue: .main
+        ) { _ in
+            try? self.saveState()
+        }
     }
 
     private var inputVector: Vector {
@@ -90,4 +100,16 @@ class ViewController: UIViewController {
         imageView.backgroundColor = .black
         imageView.layer.magnificationFilter = .nearest
     }
+
+    func saveState() throws {
+        let data = try JSONEncoder().encode(world)
+        let url = URL(fileURLWithPath: (savePath as NSString).expandingTildeInPath)
+        try data.write(to: url, options: .atomic)
+    }
+
+    func restoreState() throws {
+        let url = URL(fileURLWithPath: (savePath as NSString).expandingTildeInPath)
+        let data = try Data(contentsOf: url)
+        world = try JSONDecoder().decode(World.self, from: data)
+    }
 }