Quake that people actually play. Like look at the virality of Battle bits Remastered, the Battlefield with block characters so you can have like 200 people in the match. Games need to feel snappy and run on a lot of low tech machines, and developers are mostly never catering to that budget demographic. FPS games have a huge demand for this. The hundreds of thousands of nerds who can infodump about how incredible the Source engine feels is my proof. So yeah I think there is still a market for competitive movement game 2.0 - a team fortress 3, a titanfall 3, a quake / unreal tournament that runs well and allows community mapping. Like unironically last gens engines followed the wrong upgrade paths and there is still more performance to squeeze out (titanfall 2 using highly customized source and it looking like a AAA game rather than a source game as my proof)