Well, I love a lot of games people have already listed, and more recently, Deus Ex: HR was a contender, but none stayed my favorite. My favorite game of all time has to be Fallout 3. I love the setting, the gameplay, the weapons. Honestly, the best part for me is the setting. The desolate wastes, half-assed cities, and grotesque creatures with the 1950's esque style to items, weapons and music. Those all sell the series to me. And with the change from the original Fallout, and Fallout 2, it was a good way to introduce me to a series I love. Although, I do admit, Fallout 1, 2 and Tactics are some of the most difficult, yet fun, games I've played