(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.
Disco Elysium
The sheer joy of realising it's not "just another" RPG, slowly pulling the curtain on how intricate the worldbuilding is, discovering the main character and in turn reflecting on yourself. It's become a small addiction to watch first time streamers and let's players for me, to vicariously relive that process.
Another candidate might be Ultima 7, the interactivity and how "real" it felt in the 90s was mindblowing for kid me.