diff --git a/component/player.go b/component/player.go
index 3797188..1339b96 100644
--- a/component/player.go
+++ b/component/player.go
@@ -99,6 +99,17 @@ func FrameDataForActionTick(a PlayerAction, tick int) []FrameData {
 	return actionFrames[tick-1]
 }
 
+func FlipRect(r image.Rectangle, flip bool) image.Rectangle {
+	if !flip {
+		return r
+	}
+	return image.Rect(-r.Min.X+PlayerSize, r.Min.Y, -r.Max.X+PlayerSize, r.Max.Y)
+}
+
+func PlayerOnRightSide(p Player, o Player) bool {
+	return p.X > o.X
+}
+
 type Player struct {
 	X, Y      float64
 	VX, VY    float64
diff --git a/flags.go b/flags.go
index 9d553ab..ad64ef0 100644
--- a/flags.go
+++ b/flags.go
@@ -21,6 +21,7 @@ func parseFlags() {
 		printDebug     bool
 	)
 	flag.BoolVar(&fullscreen, "fullscreen", false, "run in fullscreen mode")
+	flag.BoolVar(&world.DisableVsync, "no-vsync", false, "turn off vsync and run at maximum fps")
 	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)")
diff --git a/game/game.go b/game/game.go
index 7c5b17b..c4f18b3 100644
--- a/game/game.go
+++ b/game/game.go
@@ -4,6 +4,7 @@ import (
 	"crypto/sha1"
 	"image/color"
 	"log"
+	"math"
 	"os"
 	"strconv"
 	"strings"
@@ -210,7 +211,7 @@ func (g *Game) applyPhysics() {
 
 		// Apply gravity.
 		if p.VY > -world.Gravity {
-			p.VY -= 1
+			p.VY -= math.Max(math.Abs(p.VY/2.5), 0.1)
 			if p.VY < -world.Gravity {
 				p.VY = -world.Gravity
 			}
@@ -240,6 +241,7 @@ func (g *Game) applyPhysics() {
 
 func (g *Game) UpdateByInputs(inputs []InputBits) {
 	var player, opponent *component.Player
+	var playerFlipped, oppFlipped bool
 	for i, input := range inputs {
 		opp := 0
 		if i == 0 {
@@ -248,6 +250,15 @@ func (g *Game) UpdateByInputs(inputs []InputBits) {
 		player = &g.Players[i]
 		opponent = &g.Players[opp]
 
+		if component.PlayerOnRightSide(*player, *opponent) { // Player is on the right side.
+			playerFlipped = true
+			oppFlipped = false
+		} else { // Opponent is on the right side.
+			playerFlipped = false
+			oppFlipped = true
+		}
+		_ = oppFlipped // TODO
+
 		playerRect := world.FloatRect(g.Players[i].X, g.Players[i].Y, g.Players[i].X+float64(component.PlayerSize), g.Players[i].Y+float64(component.PlayerSize))
 		oppRect := world.FloatRect(g.Players[opp].X, g.Players[opp].Y, g.Players[opp].X+float64(component.PlayerSize), g.Players[opp].Y+float64(component.PlayerSize))
 
@@ -256,10 +267,9 @@ func (g *Game) UpdateByInputs(inputs []InputBits) {
 
 		if player.Action != component.ActionStunned {
 			if input.isButtonOn(ButtonUp) && !component.TranslateRect(playerRect, 0, -1).Overlaps(oppRect) {
-				grounded := g.Players[i].Y == float64(component.PlayerSize)
-				// TODO check when last jump, grounded
+				grounded := g.Players[i].Y > -world.FloatValueThreshold && g.Players[i].Y < world.FloatValueThreshold
 				if grounded {
-					g.Players[i].VY = 20
+					g.Players[i].VY = world.JumpVelocity
 				}
 			}
 			if input.isButtonOn(ButtonDown) && !component.TranslateRect(playerRect, 0, 1).Overlaps(oppRect) {
@@ -290,10 +300,12 @@ func (g *Game) UpdateByInputs(inputs []InputBits) {
 
 			allFrameData := component.FrameDataForActionTick(g.Players[i].Action, g.Players[i].ActionTicksLeft)
 			for _, frame := range allFrameData {
+				frameRect := component.FlipRect(frame.R, playerFlipped)
+
 				// Apply hitbox.
 				if frame.T == component.HitboxHurt {
 					// Hit opponent.
-					if oppRect.Overlaps(component.TranslateRect(frame.R, int(player.X), int(player.Y))) {
+					if oppRect.Overlaps(component.TranslateRect(frameRect, int(player.X), int(player.Y))) {
 						// Send the opponent flying in some direction.
 						if opponent.X <= player.X { // Opponent is to the left of the player.
 							opponent.VX = -4
@@ -439,7 +451,11 @@ func (g *Game) Update() error {
 		g.RunFrame()
 	}
 
-	return gohan.Update()
+	err := gohan.Update()
+	if err != nil {
+		return err
+	}
+	return nil
 }
 
 func (g *Game) Draw(screen *ebiten.Image) {
diff --git a/main.go b/main.go
index 03193c4..7b46003 100644
--- a/main.go
+++ b/main.go
@@ -16,13 +16,18 @@ func main() {
 	ebiten.SetWindowResizingMode(ebiten.WindowResizingModeEnabled)
 	ebiten.SetWindowSize(world.DefaultScreenWidth, world.DefaultScreenHeight)
 	ebiten.SetWindowClosingHandled(true)
-	ebiten.SetFPSMode(ebiten.FPSModeVsyncOn)
 	ebiten.SetRunnableOnUnfocused(true)
 
 	parseFlags()
 
 	ebiten.SetTPS(world.TPS)
 
+	if world.DisableVsync {
+		ebiten.SetFPSMode(ebiten.FPSModeVsyncOffMaximum)
+	} else {
+		ebiten.SetFPSMode(ebiten.FPSModeVsyncOn)
+	}
+
 	g, err := game.NewGame()
 	if err != nil {
 		log.Fatal(err)
diff --git a/system/ui.go b/system/ui.go
index b22a67c..57236a3 100644
--- a/system/ui.go
+++ b/system/ui.go
@@ -180,17 +180,17 @@ func (u *UISystem) Update(e gohan.Entity) error {
 	return etk.Update()
 }
 
-func (u *UISystem) drawBox(screen *ebiten.Image, fillColor color.Color, x float64, y float64, w int, h int) {
+func (u *UISystem) drawBox(screen *ebiten.Image, fillColor color.Color, r image.Rectangle) {
 	bounds := u.hitboxImg.Bounds()
-	if bounds.Dx() != w || bounds.Dy() != h {
-		u.hitboxImg = ebiten.NewImage(w, h)
+	if bounds.Dx() != r.Dx() || bounds.Dy() != r.Dy() {
+		u.hitboxImg = ebiten.NewImage(r.Dx(), r.Dy())
 	}
 	u.hitboxImg.Clear()
 	u.hitboxImg.Fill(color.RGBA{255, 255, 255, 255})
-	u.hitboxImg.SubImage(image.Rect(2, 2, w-2, h-2)).(*ebiten.Image).Fill(fillColor)
+	u.hitboxImg.SubImage(image.Rect(2, 2, r.Dx()-2, r.Dy()-2)).(*ebiten.Image).Fill(fillColor)
 
 	// Get screen position of top left corner of player.
-	drawX, drawY := world.GameCoordsToScreen(x, y)
+	drawX, drawY := world.GameCoordsToScreen(float64(r.Min.X), float64(r.Min.Y+r.Dy()))
 
 	op := &ebiten.DrawImageOptions{}
 	op.GeoM.Translate(float64(drawX), float64(drawY))
@@ -209,31 +209,38 @@ func (u *UISystem) Draw(e gohan.Entity, screen *ebiten.Image) error {
 			return err
 		}
 	} else if world.Debug > 1 { // In-game and debug mode is enabled
-		var p *component.Player
+		var p, o *component.Player
 		for i := 0; i < 2; i++ {
 			if i == 0 {
 				p = &world.Player1
+				o = &world.Player2
 			} else {
 				p = &world.Player2
+				o = &world.Player1
 			}
 
 			if p.ActionTicksLeft != 0 {
 				// Draw a rect over stunned players.
 				if p.Action == component.ActionStunned {
+					playerRect := world.FloatRect(p.X, p.Y, p.X+float64(component.PlayerSize), p.Y+float64(component.PlayerSize))
+
 					fillColor := color.RGBA{123, 30, 255, 255}
-					u.drawBox(screen, fillColor, p.X, p.Y+component.PlayerSize, component.PlayerSize, component.PlayerSize)
+					u.drawBox(screen, fillColor, playerRect)
 					continue
 				}
 
 				// Draw frame data rects.
 				allData := component.FrameDataForActionTick(p.Action, p.ActionTicksLeft)
-				for _, data := range allData {
+				for _, frame := range allData {
+					frameRect := component.FlipRect(frame.R, component.PlayerOnRightSide(*p, *o))
+					frameRect = component.TranslateRect(frameRect, int(p.X), int(p.Y))
+
 					fillColor := color.RGBA{0, 255, 0, 255}
-					switch data.T {
+					switch frame.T {
 					case component.HitboxHurt:
 						fillColor = color.RGBA{0, 0, 255, 255}
 					}
-					u.drawBox(screen, fillColor, p.X, p.Y+float64(data.R.Dy()), data.R.Dx(), data.R.Dy())
+					u.drawBox(screen, fillColor, frameRect)
 				}
 			}
 		}
diff --git a/world/world.go b/world/world.go
index e0c906f..1797b46 100644
--- a/world/world.go
+++ b/world/world.go
@@ -15,16 +15,22 @@ const (
 
 	InternalScreenWidth, InternalScreenHeight = 854, 480
 
-	Gravity = 6.0
+	Gravity = 3
 
-	GroundHeight = 100 // TODO
+	JumpVelocity = 30
+
+	GroundHeight = 100
 
 	MaxDebug = 2
+
+	FloatValueThreshold = 0.00000001
 )
 
 var (
 	TPS = DefaultTPS
 
+	DisableVsync bool
+
 	ScreenWidth, ScreenHeight = 0, 0
 
 	CamX, CamY = 0, 0 // TODO currently static