diff --git a/Source/Engine/Actor.swift b/Source/Engine/Actor.swift
index 43fbc9e..8c9f004 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 }
     var isDead: Bool { get }
diff --git a/Source/Engine/Animation.swift b/Source/Engine/Animation.swift
index d9fa445..41257a0 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/Color.swift b/Source/Engine/Color.swift
index b0b590f..c584e7f 100644
--- a/Source/Engine/Color.swift
+++ b/Source/Engine/Color.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public struct Color {
+public struct Color: Codable {
     public var r, g, b, a: UInt8
 
     public init(r: UInt8, g: UInt8, b: UInt8, a: UInt8 = 255) {
diff --git a/Source/Engine/Effect.swift b/Source/Engine/Effect.swift
index 8d67431..3fd19e2 100644
--- a/Source/Engine/Effect.swift
+++ b/Source/Engine/Effect.swift
@@ -6,13 +6,13 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public enum EffectType {
+public enum EffectType: Int, Codable {
     case fadeIn
     case fadeOut
     case fizzleOut
 }
 
-public struct Effect {
+public struct Effect: Codable {
     public let type: EffectType
     public let color: Color
     public let duration: Double
diff --git a/Source/Engine/Monster.swift b/Source/Engine/Monster.swift
index 1eacf2f..869a76a 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/Player.swift b/Source/Engine/Player.swift
index 33c5106..11d9a66 100644
--- a/Source/Engine/Player.swift
+++ b/Source/Engine/Player.swift
@@ -6,7 +6,7 @@
 //  Copyright © 2019 Nick Lockwood. All rights reserved.
 //
 
-public enum PlayerState {
+public enum PlayerState: Int, Codable {
     case idle
     case firing
 }
diff --git a/Source/Engine/Textures.swift b/Source/Engine/Textures.swift
index d85f71f..5fd4c3d 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 12e5e8d..a042337 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 private(set) var monsters: [Monster]
     public private(set) var player: Player!
diff --git a/Source/Rampage/ViewController.swift b/Source/Rampage/ViewController.swift
index 91ccd43..6c53f93 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"
 
 public func loadMap() -> Tilemap {
     let jsonURL = Bundle.main.url(forResource: "Map", withExtension: "json")!
@@ -52,6 +53,15 @@ class ViewController: UIViewController {
         view.addGestureRecognizer(tapGesture)
         tapGesture.addTarget(self, action: #selector(fire))
         tapGesture.delegate = self
+
+        try? restoreState()
+        NotificationCenter.default.addObserver(
+            forName: UIApplication.willResignActiveNotification,
+            object: nil,
+            queue: .main
+        ) { _ in
+            try? self.saveState()
+        }
     }
 
     private var inputVector: Vector {
@@ -107,6 +117,18 @@ 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)
+    }
 }
 
 extension ViewController: UIGestureRecognizerDelegate {