(Saw this question asked on another popular link aggregation website and it got me thinking)
If you could play one game for the first time all over again, what would you choose? This might be because you want to do it all again, or because you don't think you got enough out of it the first time. It could be experiencing the game exactly as you were back then, or experiencing a game with what you know now.
For me, it's Legend of Zelda: A Link To The Past, experienced exactly as I was back in 1991.
Nothing comes close to how jaw-droppingly amazed I was by that opening sequence. The epic orchestral score, the cinematic rainstorm, creeping around in the dark... it was a generational leap above anything I'd played on 8-bit computers and consoles, and even the Megadrive. I'd love to play it again without thirty plus years of Nintendo/Zelda knowledge, or without knowing about the dark world.
There are many games that I loved and would enjoy playing for the first time, but I'm going to pick Mario and Luigi Superstar Saga. My reason being that I spent the vast majority of the game waiting for it to morph into a spiritual successor of Super Mario RPG back when I first played it, rather than giving it a chance to stand on its own as a unique and hilarious game. My preconceived idea of what I hoped the game would be really hurt my initial enjoyment of it.
For a runner up, I'll mention Kirby's Dream Land 3. In the days of Blockbuster rentals, I'd rented Kirby Super Star first, so it took me a while to get used to the more traditional Kirby powerup system where copied abilities only do one type of action each.