The buggiest game I have ever seen was/is S.T.A.L.K.E.R clear sky. It's just a short while after it's release and it's already on it's 4th or 5th patch. I had to replay the game like 7 times due to mission bugs and not being able to load saves after patch. Not to mention the artifacts that fail to appear when you're standing right over them with a top class detectors after you spent 20 minutes getting to them through radiation, fire and exploding anomalies and the ever so sweet bug fixed in the first patch that caused the grenade to stick to the players hand. However with those horrible things said about the game let me even it out. If it were any normal game, I would have thrown it out the window after the third unreloadable patch, however the gun combat, the story, the beautiful graphics, the depressing surrounding, the mutant dogs, faction wars and the fights that make crysis on hard feel like a walk in the park, more than give you reason to keep on moving.