For a lot of games, the first experience is usually the best experience. Be it because there's a twist you don't see coming, a world you've never seen before or simply the joy of discovery. So I ask the question: if given the choice, what games would you once again want to experience for the first time?
Bioshock is probably my go-to answer. I'd love to relive the experience of exploring Rapture for the first time. And of course, there's always the you-know-what.
Shadow of the Colossus and Dark Souls also rank pretty high. Shadow of the Colossus for it's, "OH MY GOD, IT'S HUGE". Dark Souls for it's, "Oooh, a ches-WHAT THE FUCK".