The top-selling game on Steam right now is a new 254-player FPS made by 4 people

I played it during testing and for a few hours since it came out to early access. It's great compared to the mediocre unfinished crap most AAA studios are putting out. The servers run smoothly, VOIP is great, there's a server browser, good gunplay. Obviously the graphics aren't the selling point, but the gameplay is fun and everything just works.