damn near perfect.
i myself find portal to be infinately entertaining, seeing as it poses challenges to you as a player, where you must rethink whatever you may know about physics, seeing as a hole in a wall in front of you, may lead to another hole 40 feet in the air pointing downwards, the world has been turned upside down in this lovely puzzle shooter. Half life 2 pretty much speaks for itself, but i must add: HAHAHAHAHA, great fun.
team fortress 2 is all out multiplayer carnage, where you choose your class, according to your wn preferences, and then go ballistic. basically just gankage for yer mates.