Out of those choices I pick Half-Life. I think Halo is way overrated. I agree with Will about the amount of guns carried but come on, you can't deny (Bungie admits it) that the Pistol is a freaking high-powered death machine. It's the best weapon in the game. Other than the first person I don't think it's that fun. The respawn in the game is crap. Me and my friends frequently respawn 2 or 3 times right where we died just to get blasted with a rocket.