diff --git a/README.md b/README.md
index 03af325..b52ff29 100644
--- a/README.md
+++ b/README.md
@@ -28,5 +28,6 @@ Please share issues and suggestions [here](https://code.rocketnine.space/tslocum
 ## Dependencies
 
 - [ebitengine](https://github.com/hajimehoshi/ebiten) - Game engine
+- [ggpo-go](https://github.com/assemblaj/ggpo) - Rollback networking library
 - [gohan](https://code.rocketnine.space/tslocum/gohan) - Entity Component System framework
 - [etk](https://code.rocketnine.space/tslocum/etk) - Graphical User Interface toolkit
diff --git a/flags.go b/flags.go
new file mode 100644
index 0000000..0248f85
--- /dev/null
+++ b/flags.go
@@ -0,0 +1,46 @@
+//go:build !js || !wasm
+// +build !js !wasm
+
+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+
+	"code.rocketnine.space/tslocum/boxbrawl/world"
+	"github.com/assemblaj/ggpo"
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+func parseFlags() {
+	var (
+		fullscreen     bool
+		hostAddress    string
+		connectAddress string
+		printDebug     bool
+	)
+	flag.BoolVar(&fullscreen, "fullscreen", false, "run in fullscreen mode")
+	flag.StringVar(&hostAddress, "host", "", "start hosting a match on specified address:port")
+	flag.StringVar(&connectAddress, "connect", "", "connect to a match at specified address:port")
+	flag.IntVar(&world.LocalPort, "local", 0, "set local port (this is not normally required)")
+	flag.BoolVar(&printDebug, "debug", false, "enable printing debug messages")
+	flag.Parse()
+
+	if fullscreen {
+		ebiten.SetFullscreen(true)
+	}
+
+	if printDebug {
+		ggpo.SetLogger(log.New(os.Stderr, "GGPO ", log.Ldate|log.Ltime|log.Lmsgprefix))
+	}
+
+	if hostAddress != "" {
+		world.ConnectPromptHost = true
+		world.ConnectPromptText = hostAddress
+		world.ConnectPromptConfirmed = true
+	} else if connectAddress != "" {
+		world.ConnectPromptText = connectAddress
+		world.ConnectPromptConfirmed = true
+	}
+}
diff --git a/flags_web.go b/flags_web.go
new file mode 100644
index 0000000..1ad7396
--- /dev/null
+++ b/flags_web.go
@@ -0,0 +1,15 @@
+//go:build js && wasm
+// +build js,wasm
+
+package main
+
+import (
+	"code.rocketnine.space/tslocum/boxbrawl/world"
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+func parseFlags() {
+	world.WASM = true
+
+	ebiten.SetFullscreen(true)
+}
diff --git a/game/game.go b/game/game.go
index a5ba73c..42d9610 100644
--- a/game/game.go
+++ b/game/game.go
@@ -1,29 +1,69 @@
 package game
 
 import (
+	"crypto/sha1"
+	"image/color"
 	"log"
 	"os"
+	"strconv"
+	"strings"
 
 	"code.rocketnine.space/tslocum/boxbrawl/entity"
 	"code.rocketnine.space/tslocum/boxbrawl/system"
 	"code.rocketnine.space/tslocum/boxbrawl/world"
 	"code.rocketnine.space/tslocum/etk"
 	"code.rocketnine.space/tslocum/gohan"
+	"github.com/assemblaj/ggpo"
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
-type Game struct{}
+var backend ggpo.Backend
 
-func NewGame() (*Game, error) {
-	g := &Game{}
+var currentPlayer = 1
 
-	entity.NewOnceEntity()
+type Game struct {
+	Players []Player
+}
 
-	gohan.AddSystem(&system.UISystem{})
+var addedGame bool
+
+func NewGame() (*Game, error) {
+	var player1 = Player{
+		X:         50,
+		Y:         50,
+		Color:     color.RGBA{255, 0, 0, 255},
+		PlayerNum: 1,
+	}
+	var player2 = Player{
+		X:         150,
+		Y:         50,
+		Color:     color.RGBA{0, 0, 255, 255},
+		PlayerNum: 2,
+	}
+	g := &Game{
+		Players: []Player{player1, player2},
+	}
+
+	if !addedGame {
+		entity.NewOnceEntity()
+		gohan.AddSystem(&system.UISystem{})
+		addedGame = true
+	}
 
 	return g, nil
 }
 
+func (g *Game) clone() (result *Game) {
+	result = &Game{}
+	*result = *g
+
+	result.Players = make([]Player, len(g.Players))
+	for i := range g.Players {
+		result.Players[i] = g.Players[i].clone()
+	}
+	return
+}
+
 func (g *Game) Layout(outsideWidth, outsideHeight int) (screenWidth, screenHeight int) {
 	if outsideWidth != world.ScreenWidth || outsideHeight != world.ScreenHeight {
 		if world.ScreenWidth != 0 || world.ScreenHeight != 0 {
@@ -35,11 +75,71 @@ func (g *Game) Layout(outsideWidth, outsideHeight int) (screenWidth, screenHeigh
 }
 
 func (g *Game) Update() error {
-	if ebiten.IsWindowBeingClosed() {
+	if ebiten.IsWindowBeingClosed() || (!world.WASM && ebiten.IsKeyPressed(ebiten.KeyEscape)) {
 		g.Exit()
 		return nil
 	}
 
+	if world.ConnectPromptConfirmed && !world.ConnectPromptActive {
+		address := ""
+		port := world.ConnectPromptText
+		if strings.ContainsRune(port, ':') {
+			split := strings.Split(port, ":")
+			if len(split) == 2 {
+				address = split[0]
+				port = split[1]
+			}
+		}
+		p, err := strconv.Atoi(port)
+		if err != nil {
+			log.Fatalf("failed to read port: %s", err)
+		}
+
+		log.Println("start networking")
+
+		localPort := world.LocalPort
+		if localPort == 0 {
+			localPort = p
+		}
+
+		numPlayers := 2
+		playerSize := 20
+		players := make([]ggpo.Player, numPlayers)
+		if world.ConnectPromptHost {
+			log.Printf("Hosting at " + address + ":" + port + "...")
+
+			players[0] = ggpo.NewLocalPlayer(playerSize, 1)
+			players[1] = ggpo.NewRemotePlayer(playerSize, 2, "127.0.0.1", localPort)
+		} else {
+			log.Printf("Connecting to " + address + ":" + port + "...")
+
+			players[0] = ggpo.NewRemotePlayer(playerSize, 1, address, p)
+			players[1] = ggpo.NewLocalPlayer(playerSize, 2)
+			currentPlayer = 2
+		}
+
+		if world.LocalPort != 0 {
+			log.Printf("Client port for connection: %d", world.LocalPort)
+		}
+
+		l := p
+		if !world.ConnectPromptHost {
+			l = localPort
+		}
+
+		g.InitNetworking(l, numPlayers, players, 0)
+
+		world.ConnectPromptActive = true
+	}
+
+	if world.ConnectPromptActive {
+		err := backend.Idle(0) // TODO Why 0?
+		if err != nil {
+			panic(err)
+		}
+		g.RunFrame()
+	}
+
 	return gohan.Update()
 }
 
@@ -53,3 +153,152 @@ func (g *Game) Draw(screen *ebiten.Image) {
 func (g *Game) Exit() {
 	os.Exit(0)
 }
+
+func (g *Game) InitNetworking(localPort int, numPlayers int, players []ggpo.Player, numSpectators int) {
+	var result error
+	var inputBits InputBits = 0
+	var inputSize int = len(encodeInputs(inputBits))
+
+	session := NewGameSession()
+
+	peer := ggpo.NewPeer(session, localPort, numPlayers, inputSize)
+	//peer := ggpo.NewSyncTest(&session, numPlayers, 8, inputSize, true)
+	backend = &peer
+	session.backend = backend
+	peer.InitializeConnection()
+	peer.Start()
+
+	//session.SetDisconnectTimeout(3000)
+	//session.SetDisconnectNotifyStart(1000)
+
+	for i := 0; i < numPlayers+numSpectators; i++ {
+		var handle ggpo.PlayerHandle
+		result = peer.AddPlayer(&players[i], &handle)
+		if players[i].PlayerType == ggpo.PlayerTypeLocal {
+			currentPlayer = int(handle)
+		}
+		if result != nil {
+			log.Fatalf("There's an issue from AddPlayer")
+		}
+		if players[i].PlayerType == ggpo.PlayerTypeLocal {
+			peer.SetFrameDelay(handle, FRAME_DELAY)
+		}
+	}
+	peer.SetDisconnectTimeout(3000)
+	peer.SetDisconnectNotifyStart(1000)
+}
+
+func (g *Game) RunFrame() {
+	input := g.ReadInputs()
+	buffer := encodeInputs(input)
+
+	//fmt.Println("Attempting to add local inputs")
+	result := backend.AddLocalInput(ggpo.PlayerHandle(currentPlayer), buffer, len(buffer))
+
+	//fmt.Println("Attempt to add local inputs complete")
+	if result == nil {
+		//fmt.Println("Attempt to add local inputs was successful")
+		var values [][]byte
+		disconnectFlags := 0
+
+		//fmt.Println("Attempting to synchronize inputs")
+		values, result = backend.SyncInput(&disconnectFlags)
+		if result == nil {
+			//fmt.Println("Attempt synchronize inputs was sucessful")
+			inputs := decodeInputs(values)
+			//fmt.Println("Advancing Frame from game loop")
+			g.AdvanceFrame(inputs, disconnectFlags)
+		} else {
+			//fmt.Printf("Attempt synchronize inputs was unsuccessful: %s\n", result)
+		}
+	} else {
+		//fmt.Printf("Attempt to add local inputs unsuccessful: %s\n", result)
+	}
+}
+
+func (g *Game) AdvanceFrame(inputs []InputBits, disconnectFlags int) {
+	log.Println("ADVANCE FRAME")
+
+	g.UpdateByInputs(inputs)
+	err := backend.AdvanceFrame(uint32(g.Checksum()))
+	if err != nil {
+		panic(err)
+	}
+}
+
+func (g *Game) UpdateByInputs(inputs []InputBits) {
+	for i, input := range inputs {
+		if input.isButtonOn(int(ebiten.KeyArrowUp)) {
+			g.Players[i].Y--
+		}
+		if input.isButtonOn(int(ebiten.KeyArrowDown)) {
+			g.Players[i].Y++
+		}
+		if input.isButtonOn(int(ebiten.KeyArrowLeft)) {
+			g.Players[i].X--
+		}
+		if input.isButtonOn(int(ebiten.KeyArrowRight)) {
+			g.Players[i].X++
+		}
+		if input.isButtonOn(int(ebiten.KeyW)) {
+			g.Players[i].Y--
+		}
+		if input.isButtonOn(int(ebiten.KeyS)) {
+			g.Players[i].Y++
+		}
+		if input.isButtonOn(int(ebiten.KeyA)) {
+			g.Players[i].X--
+		}
+		if input.isButtonOn(int(ebiten.KeyD)) {
+			g.Players[i].X++
+		}
+	}
+}
+
+func (g *Game) ReadInputs() InputBits {
+	var in InputBits
+
+	if ebiten.IsKeyPressed(ebiten.KeyArrowUp) {
+		in.setButton(int(ebiten.KeyArrowUp))
+	}
+	if ebiten.IsKeyPressed(ebiten.KeyArrowDown) {
+		in.setButton(int(ebiten.KeyArrowDown))
+	}
+	if ebiten.IsKeyPressed(ebiten.KeyArrowLeft) {
+		in.setButton(int(ebiten.KeyArrowLeft))
+	}
+	if ebiten.IsKeyPressed(ebiten.KeyArrowRight) {
+		in.setButton(int(ebiten.KeyArrowRight))
+	}
+	return in
+}
+
+func (g *Game) ReadInputsP2() InputBits {
+	var in InputBits
+
+	if ebiten.IsKeyPressed(ebiten.KeyW) {
+		in.setButton(int(ebiten.KeyW))
+	}
+	if ebiten.IsKeyPressed(ebiten.KeyS) {
+		in.setButton(int(ebiten.KeyS))
+	}
+	if ebiten.IsKeyPressed(ebiten.KeyA) {
+		in.setButton(int(ebiten.KeyA))
+	}
+	if ebiten.IsKeyPressed(ebiten.KeyD) {
+		in.setButton(int(ebiten.KeyD))
+	}
+	return in
+
+}
+
+func (g *Game) Checksum() int {
+	h := sha1.New()
+	h.Write([]byte(g.String()))
+	toSum := h.Sum(nil)
+	sum := 0
+	for _, v := range toSum {
+		sum += int(v)
+	}
+	return sum
+}
diff --git a/game/inputs.go b/game/inputs.go
new file mode 100644
index 0000000..beea2c0
--- /dev/null
+++ b/game/inputs.go
@@ -0,0 +1,90 @@
+package game
+
+import (
+	"bytes"
+	"encoding/gob"
+	"fmt"
+	"log"
+)
+
+type Input struct {
+	ButtonMap int
+}
+
+type InputBits int
+
+func (i *InputBits) isButtonOn(button int) bool {
+	return *i&(1<<button) > 0
+}
+
+func (i *InputBits) setButton(button int) {
+	*i |= (1 << button)
+}
+
+func readI32(b []byte) int32 {
+	if len(b) < 4 {
+		return 0
+	}
+	return int32(b[0]) | int32(b[1])<<8 | int32(b[2])<<16 | int32(b[3])<<24
+}
+
+func writeI32(i32 int32) []byte {
+	b := []byte{byte(i32), byte(i32 >> 8), byte(i32 >> 16), byte(i32 >> 24)}
+	return b
+}
+
+func (i *Input) isButtonOn(button int) bool {
+	return i.ButtonMap&(1<<button) > 0
+}
+
+func (i *Input) setButton(button int) {
+	i.ButtonMap |= (1 << button)
+}
+
+func (i Input) String() string {
+	return fmt.Sprintf("Input %d", i.ButtonMap)
+}
+
+func NewInput() Input {
+	return Input{}
+}
+
+func encodeInputs(inputs InputBits) []byte {
+	return writeI32(int32(inputs))
+}
+
+func decodeInputs(buffer [][]byte) []InputBits {
+	var inputs = make([]InputBits, len(buffer))
+	for i, b := range buffer {
+		inputs[i] = InputBits(readI32(b))
+	}
+	return inputs
+}
+
+func decodeInputsGob(buffer [][]byte) []Input {
+	var inputs = make([]Input, len(buffer))
+	for i, b := range buffer {
+		var buf bytes.Buffer = *bytes.NewBuffer(b)
+		dec := gob.NewDecoder(&buf)
+		err := dec.Decode(&inputs[i])
+		if err != nil {
+			log.Printf("decode error: %s. Returning empty input\n", err)
+			// hack
+			inputs[i] = NewInput()
+			//panic("eof")
+		} else {
+			log.Printf("inputs properly decoded: %s\n", inputs[i])
+		}
+	}
+	return inputs
+}
+
+func encodeInputsGob(inputs Input) []byte {
+	var buf bytes.Buffer
+	enc := gob.NewEncoder(&buf)
+	err := enc.Encode(&inputs)
+	if err != nil {
+		log.Fatal("encode error ", err)
+	}
+	return buf.Bytes()
+}
diff --git a/game/player.go b/game/player.go
new file mode 100644
index 0000000..2001ea9
--- /dev/null
+++ b/game/player.go
@@ -0,0 +1,19 @@
+package game
+
+import "image/color"
+
+type Player struct {
+	X         float64
+	Y         float64
+	Color     color.Color
+	PlayerNum int
+}
+
+func (p *Player) clone() Player {
+	result := Player{}
+	result.X = p.X
+	result.Y = p.Y
+	result.Color = p.Color
+	result.PlayerNum = p.PlayerNum
+	return result
+}
diff --git a/game/session.go b/game/session.go
new file mode 100644
index 0000000..d7e0c6b
--- /dev/null
+++ b/game/session.go
@@ -0,0 +1,102 @@
+package game
+
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/gob"
+	"fmt"
+	"log"
+
+	"github.com/assemblaj/ggpo"
+)
+
+const FRAME_DELAY int = 2
+
+type GameSession struct {
+	backend    ggpo.Backend
+	game       *Game
+	saveStates map[int]*Game
+}
+
+func NewGameSession() *GameSession {
+	g := &GameSession{}
+	game, _ := NewGame()
+	g.game = game
+	g.saveStates = make(map[int]*Game)
+	return g
+}
+
+func (g *GameSession) SaveGameState(stateID int) int {
+	g.saveStates[stateID] = g.game.clone()
+	checksum := calculateChecksum([]byte(g.saveStates[stateID].String()))
+	return checksum
+}
+
+func calculateChecksum(buffer []byte) int {
+	cSum := md5.Sum(buffer)
+	checksum := 0
+	for i := 0; i < len(cSum); i++ {
+		checksum += int(cSum[i])
+	}
+	return checksum
+}
+
+func (g *GameSession) LoadGameState(stateID int) {
+	*g.game = *g.saveStates[stateID]
+}
+
+func (g *GameSession) LogGameState(fileName string, buffer []byte, len int) {
+	var game2 Game
+	var buf bytes.Buffer = *bytes.NewBuffer(buffer)
+	dec := gob.NewDecoder(&buf)
+	err := dec.Decode(&game2)
+	if err != nil {
+		log.Fatal("decode error:", err)
+	}
+	log.Printf("%s Game State: %s\n", fileName, game2.String())
+}
+
+func (g *GameSession) SetBackend(backend ggpo.Backend) {
+}
+
+func (g *Game) String() string {
+	return fmt.Sprintf("%s : %s ", g.Players[0].String(), g.Players[1].String())
+}
+
+func (p *Player) String() string {
+	return fmt.Sprintf("Player %d: X:%f Y:%f Color: %s", p.PlayerNum, p.X, p.Y, p.Color)
+}
+
+func (g *GameSession) AdvanceFrame(flags int) {
+	fmt.Println("Advancing frame from callback. ")
+	var discconectFlags int
+
+	// Make sure we fetch the inputs from GGPO and use these to update
+	// the game state instead of reading from the keyboard.
+	inputs, result := g.backend.SyncInput(&discconectFlags)
+	if result == nil {
+		input := decodeInputs(inputs)
+		g.game.AdvanceFrame(input, discconectFlags)
+	}
+}
+
+func (g *GameSession) OnEvent(info *ggpo.Event) {
+	switch info.Code {
+	case ggpo.EventCodeConnectedToPeer:
+		log.Println("EventCodeConnectedToPeer")
+	case ggpo.EventCodeSynchronizingWithPeer:
+		log.Println("EventCodeSynchronizingWithPeer")
+	case ggpo.EventCodeSynchronizedWithPeer:
+		log.Println("EventCodeSynchronizedWithPeer")
+	case ggpo.EventCodeRunning:
+		log.Println("EventCodeRunning")
+	case ggpo.EventCodeDisconnectedFromPeer:
+		log.Println("EventCodeDisconnectedFromPeer")
+	case ggpo.EventCodeTimeSync:
+		log.Println("EventCodeTimeSync")
+	case ggpo.EventCodeConnectionInterrupted:
+		log.Println("EventCodeconnectionInterrupted")
+	case ggpo.EventCodeConnectionResumed:
+		log.Println("EventCodeconnectionInterrupted")
+	}
+}
diff --git a/go.mod b/go.mod
index 241ccd8..dec7a07 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.19
 require (
 	code.rocketnine.space/tslocum/etk v0.0.0-20230103193701-368514415e01
 	code.rocketnine.space/tslocum/gohan v1.0.0
+	github.com/assemblaj/ggpo v0.0.0-20230105182823-b13b11d28a8e
 	github.com/hajimehoshi/ebiten/v2 v2.4.15
 )
 
@@ -14,9 +15,10 @@ require (
 	github.com/go-gl/glfw/v3.3/glfw v0.0.0-20221017161538-93cebf72946b // indirect
 	github.com/hajimehoshi/file2byteslice v1.0.0 // indirect
 	github.com/jezek/xgb v1.1.0 // indirect
-	golang.org/x/exp/shiny v0.0.0-20221230185412-738e83a70c30 // indirect
-	golang.org/x/image v0.2.0 // indirect
+	golang.org/x/exp v0.0.0-20230105000112-eab7a2c85304 // indirect
+	golang.org/x/exp/shiny v0.0.0-20230105000112-eab7a2c85304 // indirect
+	golang.org/x/image v0.3.0 // indirect
 	golang.org/x/mobile v0.0.0-20221110043201-43a038452099 // indirect
-	golang.org/x/sys v0.3.0 // indirect
-	golang.org/x/text v0.5.0 // indirect
+	golang.org/x/sys v0.4.0 // indirect
+	golang.org/x/text v0.6.0 // indirect
 )
diff --git a/go.sum b/go.sum
index 59c3265..8830a5a 100644
--- a/go.sum
+++ b/go.sum
@@ -5,6 +5,8 @@ code.rocketnine.space/tslocum/gohan v1.0.0/go.mod h1:12yOt5Ygl/RVwnnZSVZRuS1W6gC
 code.rocketnine.space/tslocum/messeji v1.0.2 h1:3/68FnXWaBDMhfUGb8FvNpVgAHY8DX+VL7pyA/CcY94=
 code.rocketnine.space/tslocum/messeji v1.0.2/go.mod h1:bSXsyjvKhFXQ7GsUxWZdO2JX83xOT/VTqFCR04thk+c=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/assemblaj/ggpo v0.0.0-20230105182823-b13b11d28a8e h1:d/uJpkRgHj5EJ06CX0TFFQLfvAeHlfWY+xfLUBkVeus=
+github.com/assemblaj/ggpo v0.0.0-20230105182823-b13b11d28a8e/go.mod h1:ZKiAYEZgxDlGHGeP/VZsv1+xIRo9kQpgUFmjP/PR0lQ=
 github.com/ebitengine/purego v0.0.0-20220905075623-aeed57cda744/go.mod h1:Eh8I3yvknDYZeCuXH9kRNaPuHEwvXDCk378o9xszmHg=
 github.com/ebitengine/purego v0.1.1 h1:HI8nW+LniW9Yb34k34jBs8nz+PNzsw68o7JF8jWFHHE=
 github.com/ebitengine/purego v0.1.1/go.mod h1:Eh8I3yvknDYZeCuXH9kRNaPuHEwvXDCk378o9xszmHg=
@@ -36,13 +38,15 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56/go.mod h1:JhuoJpWY28nO4Vef9tZUw9qufEGTyX1+7lmHxV5q5G4=
-golang.org/x/exp/shiny v0.0.0-20221230185412-738e83a70c30 h1:GoCh95fUWm4yMPxPDXFjbjwUFoO+RJy052MW5+PWh3s=
-golang.org/x/exp/shiny v0.0.0-20221230185412-738e83a70c30/go.mod h1:UH99kUObWAZkDnWqppdQe5ZhPYESUw8I0zVV1uWBR+0=
+golang.org/x/exp v0.0.0-20230105000112-eab7a2c85304 h1:YUqj+XKtfrn3kXjFIiZ8jwKROD7ioAOOHUuo3ZZ2opc=
+golang.org/x/exp v0.0.0-20230105000112-eab7a2c85304/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
+golang.org/x/exp/shiny v0.0.0-20230105000112-eab7a2c85304 h1:ezMmyIKsGPwRz+IHa53wCpw87I2TremhqQ8o79ytDEk=
+golang.org/x/exp/shiny v0.0.0-20230105000112-eab7a2c85304/go.mod h1:UH99kUObWAZkDnWqppdQe5ZhPYESUw8I0zVV1uWBR+0=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.1.0/go.mod h1:iyPr49SD/G/TBxYVB/9RRtGUT5eNbo2u4NamWeQcD5c=
-golang.org/x/image v0.2.0 h1:/DcQ0w3VHKCC5p0/P2B0JpAZ9Z++V2KOo2fyU89CXBQ=
-golang.org/x/image v0.2.0/go.mod h1:la7oBXb9w3YFjBqaAwtynVioc1ZvOnNteUNrifGNmAI=
+golang.org/x/image v0.3.0 h1:HTDXbdK9bjfSWkPzDJIw89W8CAtfFGduujWs33NLLsg=
+golang.org/x/image v0.3.0/go.mod h1:fXd9211C/0VTlYuAcOhW8dY/RtEJqODXOWBDpmYBf+A=
 golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
 golang.org/x/mobile v0.0.0-20190415191353-3e0bab5405d6/go.mod h1:E/iHnbuqvinMTCcRqshq8CkpyQDoeVncDDYHnLhea+o=
 golang.org/x/mobile v0.0.0-20220722155234-aaac322e2105/go.mod h1:pe2sM7Uk+2Su1y7u/6Z8KJ24D7lepUjFZbhFOrmDfuQ=
@@ -73,8 +77,8 @@ golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220712014510-0a85c31ab51e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220818161305-2296e01440c6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
-golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.4.0 h1:Zr2JFtRQNX3BCZ8YtxRE9hNJYC8J6I1MVbMg6owUp18=
+golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -82,8 +86,8 @@ golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.4.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
-golang.org/x/text v0.5.0 h1:OLmvp0KP+FVG99Ct/qFiL/Fhk4zp4QQnZ7b2U+5piUM=
-golang.org/x/text v0.5.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.6.0 h1:3XmdazWV+ubf7QgHSTWeykHOci5oeekaGJBLkrkaw4k=
+golang.org/x/text v0.6.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190312151545-0bb0c0a6e846/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
diff --git a/main.go b/main.go
index e312b2b..8b22545 100644
--- a/main.go
+++ b/main.go
@@ -20,18 +20,13 @@ func main() {
 	ebiten.SetTPS(world.TPS)
 	ebiten.SetRunnableOnUnfocused(true)
 
-	//parseFlags()
+	parseFlags()
 
 	g, err := game.NewGame()
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	// TODO
-	if false {
-		world.ConnectPromptVisible = true
-	}
-
 	sigc := make(chan os.Signal, 1)
 	signal.Notify(sigc,
 		syscall.SIGINT,
diff --git a/system/ui.go b/system/ui.go
index 5758daf..775eb68 100644
--- a/system/ui.go
+++ b/system/ui.go
@@ -2,7 +2,6 @@ package system
 
 import (
 	"fmt"
-	"log"
 
 	"code.rocketnine.space/tslocum/boxbrawl/component"
 	"code.rocketnine.space/tslocum/boxbrawl/world"
@@ -17,8 +16,15 @@ const uiStartPrompt = `Box Brawl
 `
 const uiComputerPrompt = `Press <Enter> to play against the computer.`
 const uiHostPrompt = `Press <H> to host a match against a remote player.`
+const uiHostInfoPrompt = `Type a port to host a match against a remote player.`
+const uiHostStartPrompt = `Press <Enter> to start hosting.`
 const uiRemotePrompt = `Type an IP address and port (address:port) to play against a remote player.`
 const uiConnectPrompt = `Press <Enter> to connect.`
+const uiBrowserPrompt = `Playing against remote players is unavailable in the browser version.
+
+Download Box Brawl for Windows or Linux to play against remote players.`
+const uiHostListeningPrompt = `Waiting for a connection on %s...`
+const uiClientConnectingPrompt = `Connecting to %s...`
 
 type UISystem struct {
 	*component.Once
@@ -38,7 +44,6 @@ func (u *UISystem) initialize() {
 	inputDemo.AddChild(u.buffer)
 
 	etk.SetRoot(inputDemo)
-
 	etk.Layout(world.ScreenWidth, world.ScreenHeight)
 
 	u.debugImg = ebiten.NewImage(128, 128)
@@ -49,15 +54,31 @@ func (u *UISystem) initialize() {
 func (u *UISystem) updateBuffer() {
 	prompt := []byte(uiStartPrompt)
 
-	promptEntered := len(world.ConnectPromptText) != 0
-	if promptEntered {
-		prompt = append(prompt, []byte("\n\n"+world.ConnectPromptText)...)
-		prompt = append(prompt, []byte("\n\n"+uiConnectPrompt)...)
-		prompt = append(prompt, []byte("\n\n"+uiRemotePrompt)...)
-	} else {
+	if world.WASM {
 		prompt = append(prompt, []byte("\n\n"+uiComputerPrompt)...)
-		prompt = append(prompt, []byte("\n\n"+uiHostPrompt)...)
-		prompt = append(prompt, []byte("\n\n"+uiRemotePrompt)...)
+		prompt = append(prompt, []byte("\n\n"+uiBrowserPrompt)...)
+	} else if world.ConnectPromptActive {
+		if world.ConnectPromptHost {
+			prompt = append(prompt, []byte("\n\n"+fmt.Sprintf(uiHostListeningPrompt, world.ConnectPromptText))...)
+		} else {
+			prompt = append(prompt, []byte("\n\n"+fmt.Sprintf(uiClientConnectingPrompt, world.ConnectPromptText))...)
+		}
+	} else {
+		promptEntered := len(world.ConnectPromptText) != 0
+		if promptEntered || world.ConnectPromptHost {
+			prompt = append(prompt, []byte("\n\n"+world.ConnectPromptText)...)
+			if world.ConnectPromptHost {
+				prompt = append(prompt, []byte("\n\n"+uiHostInfoPrompt)...)
+				prompt = append(prompt, []byte("\n\n"+uiHostStartPrompt)...)
+			} else {
+				prompt = append(prompt, []byte("\n\n"+uiConnectPrompt)...)
+				prompt = append(prompt, []byte("\n\n"+uiRemotePrompt)...)
+			}
+		} else {
+			prompt = append(prompt, []byte("\n\n"+uiComputerPrompt)...)
+			prompt = append(prompt, []byte("\n\n"+uiHostPrompt)...)
+			prompt = append(prompt, []byte("\n\n"+uiRemotePrompt)...)
+		}
 	}
 
 	u.buffer.Clear()
@@ -73,55 +94,66 @@ func (u *UISystem) Update(e gohan.Entity) error {
 		return nil
 	}
 
-	var a string
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit0) {
-		a += "0"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit1) {
-		a += "1"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit2) {
-		a += "2"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit3) {
-		a += "3"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit4) {
-		a += "4"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit5) {
-		a += "5"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit6) {
-		a += "6"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit7) {
-		a += "7"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit8) {
-		a += "8"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyDigit9) {
-		a += "9"
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyPeriod) {
-		a += "."
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeySemicolon) && ebiten.IsKeyPressed(ebiten.KeyShift) {
-		a += ":"
-	}
-	if a != "" {
-		world.ConnectPromptText += a
-		u.updateBuffer()
-	}
-	if inpututil.IsKeyJustPressed(ebiten.KeyBackspace) && len(world.ConnectPromptText) != 0 {
-		world.ConnectPromptText = world.ConnectPromptText[:len(world.ConnectPromptText)-1]
-		u.updateBuffer()
+	if !world.WASM {
+		if len(world.ConnectPromptText) == 0 && ebiten.IsKeyPressed(ebiten.KeyH) {
+			world.ConnectPromptHost = true
+			u.updateBuffer()
+		}
+
+		var a string
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit0) {
+			a += "0"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit1) {
+			a += "1"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit2) {
+			a += "2"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit3) {
+			a += "3"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit4) {
+			a += "4"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit5) {
+			a += "5"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit6) {
+			a += "6"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit7) {
+			a += "7"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit8) {
+			a += "8"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyDigit9) {
+			a += "9"
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyPeriod) {
+			a += "."
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeySemicolon) && ebiten.IsKeyPressed(ebiten.KeyShift) {
+			a += ":"
+		}
+		if a != "" {
+			world.ConnectPromptText += a
+			u.updateBuffer()
+		}
+		if inpututil.IsKeyJustPressed(ebiten.KeyBackspace) {
+			if len(world.ConnectPromptText) != 0 {
+				world.ConnectPromptText = world.ConnectPromptText[:len(world.ConnectPromptText)-1]
+				u.updateBuffer()
+			} else if world.ConnectPromptHost {
+				world.ConnectPromptHost = false
+				u.updateBuffer()
+			}
+		}
 	}
 
 	if inpututil.IsKeyJustPressed(ebiten.KeyEnter) || inpututil.IsKeyJustPressed(ebiten.KeyKPEnter) {
-		log.Println("Start game")
-		return nil
+		world.ConnectPromptConfirmed = true
 	}
 
 	return etk.Update()
diff --git a/world/world.go b/world/world.go
index 7363fdd..a389ca8 100644
--- a/world/world.go
+++ b/world/world.go
@@ -10,9 +10,15 @@ const (
 var (
 	ScreenWidth, ScreenHeight = 0, 0
 
+	LocalPort int
+
 	ConnectPromptVisible   = true
 	ConnectPromptText      string
+	ConnectPromptHost      bool
 	ConnectPromptConfirmed bool
+	ConnectPromptActive    bool
 
 	Debug = 1
+
+	WASM bool
 )