Frantic, circular demon-dodger Circa Infinity [official site] has just been released. I'm watching the release trailer now and I must say it adds more colours than I ever saw when I was playing a build. I'm now jealous and about to boot it back up for Reasons.
The idea is you flip back and forth on the edge of a circle, avoiding the minions of hell, until you find an opportunity to jump inward to the next circle.
I've not played a launch build but, from the one I did try out, I remember it being partway between the Seven Nation Army video and Super Hexagon - frantic, rhythmic and recursive.
Here's the link to the free demo which contains the first 10 levels and a boss fight. You can pick up the full version for £6.99 (or a bit cheaper with the launch discount) for Windows and Mac. It's also on Itch and through a Humble Store widget on its site, coming DRM-free and giving a Steam key too.