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.
Skyrim and Zelda obscure?
Also I’m not going to challenge the earnings of Clash of Clans, but, why is it the most influential?
Because it’s taught everyone that the cash cow is low effort, microtransaction laden “free” to play games loaded to the gills with slot machine and gatcha mechanics and other psychological manipulation tactics.
If you as a game publisher want to make big bucks, you have to make one of those. Which is why everything is becoming exactly that nowadays.