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.
The hallmark of roguelikes is procedural generation, permanent death and no overarching progression, like the titular game Rogue. Roguelites (I know, one letter difference who cares) have overarching progression lines that make the game easier as you play it. Extreme difficulty as part of the roguelike formula is expected, since runs where you don’t become very powerful very quickly happen, and the games are often balanced against some of the better possible runs.
Gungeon is punishing, but I regret to inform you you are FAR from too weak to finish floor 2 with the default kit of any character. Bashing your head against a challenge is fine as long as you’re learning something every time you don’t make it through, gungeon is simply a game where getting hit at all is really bad.
All that said, gungeon isn’t the highest quality roguelike or roguelite. That’s probably SLASH’EM (roguelike) or Elona (Roguelike(?)), and Hades (roguelite) or Windblown (roguelite, still in development). I won’t even recommend roguelikes without graphics because the average age in this thread seems mighty low.