That's a pretty general question. Games that I had the most fun with include the Metal Gear series (Revengeance was the craziest and the most fun to play, imo), the Resident Evil series, Monster Hunter Tri, Minecraft, most Mario and Zelda titles, and, of course, Smash Bros. However, the games that have influenced me the most and left the biggest impact on me include Shadow of the Colossus, Journey, and Brothers: A Tale of Two Sons. In a world where exposition dumps have to explain away all the mystery in the game (I'm looking at you, MGS), I find that most of the enjoyment I get out of the game comes from speculating why things are the way they are. A lot of people feel that way about Dark Souls, but I personally was too distracted with trying not to die to really become immersed in the game's setting.