Steam Next Fest is a semi-annual event on Steam showcasing demos for upcoming games. They're limited time only demos, so you have to jump on it now if you're interested to try them. The current Next Fest ends on Monday, so you have basically the weekend to try them out. Here are some of the better demos I've tried so far.
Vampire Crawlers: from the Vampire Survivor people, it's a dungeon crawler roguelike card-battler. I know that sounds terrible, but it's awesome. I will 100% be buying this when it comes out.
The Eternal Life of Goldman: this one's a platformer, sort of similar to Rayman Legends, but with a conceit similar to NES Ducktales. You bounce on a pogostick-like cane. The graphics are GORGEOUS. Kind of similar to Cuphead, but a bit more refined.
Scott Pilgrim EX: A sequel to Scott Pilgrim vs The World, the great pixel graphic style with all the fun of a brawler, and the elder Millennial references.
Those have been the standouts so far, but I'll make some more posts as the weekend goes on.