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.
Mount and Blade Warband.
So many games you start off or become something great. In Skyrim you’re the dragonborn, you become great but you were always going to. The world is huge and immersive, but you’re always going to be important in the world.
In warband, you’re a nobody. You’ll always be a nobody unless you do something. Trade, fight, quest or scheme. The world will continue with or without you. Your favourite faction might get wiped out and you can do something about it or not. There’s no guarantee of victory, and what you decide as a win condition is up to you.
It is the ultimate sandbox, but the original is janky. The solution; mods. An incredibly dedicated modding community elevates this game into my most played game. The lord of the rings mod is both the best way to get into the game and in my opinion the best video game adaptation of a movie (just in front of kotor).
TL:DR: Warband makes it ok to suck and makes you earn your victory. You might not think that’s fun, but trust me it can be.