For me it’s first person puzzle games. I can think of maybe a dozen off the top of my head that came out in the last decade. I especially enjoy when they’re open world. The ability to just quit a puzzle that’s stumped you and go try something else for a little bit is incredibly refreshing.
If you’re looking for the Quake brand of arena shooters, I feel like you’re getting a lot of those these days. If you’re looking for the era just after that, which Halo would fall in, I’m also looking for that type of game, so the nostalgia that fuels indie game design is probably only a few years away from delivering us that sort of game again. Maybe that new TimeSplitters or Perfect Dark game will be good.