Prevent default on arrow keys and space

scripts/game.js

@@ -31,6 +31,14 @@ var Game = {
   keysDown: {},
   start: function() {
     addEventListener('keydown', function(e) {
+      switch(e.keyCode) {
+        case 37:
+        case 38:
+        case 39:
+        case 40:
+        case 32:
+          e.preventDefault();
+      }
       Game.keysDown[e.keyCode] = true;
     }, false);
 
@@ -234,17 +242,14 @@ var MainMenu = new Scene();
         document.title = alternate ? 'SoundVoyager' : 'audventure';
         break;
       case 38:
-        e.preventDefault();
         soundManager.play('cursor');
         selected = (selected + games.length -1) % games.length;
         break;
       case 40:
-        e.preventDefault();
         soundManager.play('cursor');
         selected = (selected + 1) % games.length;
         break;
       case 32:
-        e.preventDefault();
       case 13:
         soundManager.play('confirm');
         games[selected].start();