Fun... For a time. The best part is that you can get the zombies to push the double decker into a corner, have your dog in front of you, and they are practically forced to come at you one by one.. And you can keep wiping them out in short order.
Silverknight you press ctrl + w and the game will start. The first level you get debriefed by master chief after which you continue on the Amazon river with Bruce lee. Kill him immediately. He's a traitor.