diff --git a/lib/demo/bowling.lua b/lib/demo/bowling.lua
index 23d7bd5..ed69ec0 100644
--- a/lib/demo/bowling.lua
+++ b/lib/demo/bowling.lua
@@ -67,7 +67,7 @@ function init_event()
     reference_pin:setPosition(0, 0, lane_bottom - maxz - 0.1)
     reference_ball = ag.createSphere(0.3)
     reference_ball:setColor(0.7, 0.1, 0.9)
-    reference_ball:setMass(50)
+    reference_ball:setMass(10)
     reference_ball:setPosition(0, -2, -1.5)
     resetPins()
     setupStars()
@@ -76,10 +76,15 @@ function init_event()
     target_x = 0
     game_state = "waiting"
     last_update_time = ag.elapsedTime()
+    mouse_moved = false
+    setCamera()
+end
+
+function setCamera()
+    ag.setCamera(position_x, -10, 5, target_x, 20, 0)
 end
 
 function update_event()
-    ag.setCamera(position_x, -10, 5, target_x, 20, 0)
     local now = ag.elapsedTime()
     if (ag.isKeyDown("a") or ag.isKeyDown("left")) then
         position_x = position_x - (now - last_update_time) / 300
@@ -94,17 +99,21 @@ function update_event()
         end
     end
     last_update_time = now
+    setCamera()
 
     ag.callList(stars)
 end
 
 function mouse_motion_event(x, y, xrel, yrel)
-    target_x = target_x + xrel / 100
-    if (target_x < -2) then
-        target_x = -2
-    elseif (target_x > 2) then
-        target_x = 2
+    if (mouse_moved) then
+        target_x = target_x + xrel / 100
+        if (target_x < -2) then
+            target_x = -2
+        elseif (target_x > 2) then
+            target_x = 2
+        end
     end
+    mouse_moved = true
 end
 
 function drawFrameScore(width, height, frame, fs)
@@ -148,9 +157,12 @@ end
 
 function update_overlay_event(width, height)
     drawScore(width, height)
-    if (game_state == "get_power" or game_state == "launched") then
+    if (game_state == "get_power" or game_state == "get_accuracy" or game_state == "launched") then
         drawPowerBar(width, height)
     end
+    if (game_state == "get_accuracy" or game_state == "launched") then
+        drawAccuracyBar(width, height)
+    end
 end
 
 function mousebutton_down_event(button, x, y)
@@ -158,6 +170,8 @@ function mousebutton_down_event(button, x, y)
         if (game_state == "waiting") then
             getPower()
         elseif (game_state == "get_power") then
+            getAccuracy()
+        elseif (game_state == "get_accuracy") then
             launchBall()
         end
     end
@@ -170,11 +184,26 @@ function getPower()
     power_direction = 1
 end
 
+function getAccuracy()
+    game_state = "get_accuracy"
+    accuracy = 0
+    accuracy_last_time = ag.elapsedTime()
+    accuracy_direction = 1
+end
+
 function launchBall()
     game_state = "launched"
     launch_time = ag.elapsedTime()
     bowling_ball = reference_ball:clone()
-    bowling_ball:setPosition(position_x, -10, 4)
+    bowling_ball:setPosition(position_x, -10, 1.31)
+    local fx = target_x + accuracy - position_x
+    local fy = 30               -- should match setCamera()'s dy
+    local d = math.sqrt(fx*fx + fy*fy)
+    fx = fx / d
+    fy = fy / d
+    local force = 200000
+    force = force * 0.5 + force * 0.5 * power
+    bowling_ball:addForce(fx * force, fy * force, 0)
 end
 
 function drawPowerBar(width, height)
@@ -197,3 +226,23 @@ function drawPowerBar(width, height)
     ag.fillRect(0.1, 1, 0.1, bar_width - 2, (bar_height - 2) * power,
         width - 50 - bar_width / 2, height / 2)
 end
+
+function drawAccuracyBar(width, height)
+    local bar_width = 400
+    local bar_height = 60
+    if (game_state == "get_accuracy") then
+        local now = ag.elapsedTime()
+        accuracy = accuracy + (now - accuracy_last_time) / 250 * accuracy_direction
+        if (accuracy > 1) then
+            accuracy = 1
+            accuracy_direction = -1
+        elseif (accuracy < -1) then
+            accuracy = -1
+            accuracy_direction = 1
+        end
+        accuracy_last_time = now
+    end
+    ag.drawRect(1, 1, 1, bar_width, bar_height, width / 2, 50 + bar_height / 2)
+    ag.drawLine(1, 1, 1, width / 2, 50, width / 2, 50 + bar_height)
+    ag.fillRect(0.1, 1, 0.1, 3, bar_height - 2, width / 2 + (bar_width - 4) / 2 * accuracy, 50 + bar_height / 2)
+end