Rules: just pick 1 and explain why.
I’ve been playing since the NES and despite being from a low income family I had the luck of being able to play and own many consoles over the 3 decades of my life, plus some pc.
If you ask me right now? Resident Evil 4 (2005).
A before and after in gaming, to this day still extremely fun to play even for casuals but 20 years ago it was THE masterpiece. And everyone took notice of it, everyone played it, even players that didn’t cared about resident evil. The gameplay was so good that it got photocopied by everyone right after in the action genre.
Arguably the last big innovator in videogames minus Minecraft and… PUBG (Fortnite did it better I know).
Try to NOT pick your favourite game, that’s a different thing.
Wow took over my life for a while there, and then again with WoTLK. The 2v2 and 3v3 arenas were so much fun. The cool thing was that it wasn’t grindy in the beginning, you could just run quests at your level and level up at a reasonable pace while exploring the game. I had played Everquest before WoW and that game required so much grinding just to get a level, sometimes it would take weeks.