Himno's silent protagonist carries a giant sword on their back—but doesn't ever use it. This is a platformer with no enemies in which you can never die, leaving you to relax across an infinite number of procedurally-generated levels while wall-running, sliding and interacting with lifts. Best of all, it's completely free, and available now on Steam.
It's from the creator of Medieval Shopkeeper Simulator, an Early Access game I've heard good things about. Developer David Moralejo Sánchez says he created Himno "a long time ago" as a "private project which I played to de-stress myself", and now he's releasing it out into the world.
Levels have very few light sources, so you never know what to expect when you pull yourself over the next ledge. The mellow soundtrack responds to your actions, as do floating orbs of light spread throughout the level, some of which will follow you and help illuminate the path ahead.
Watch the trailer, above, to get an idea of what to expect, and grab it here if you're interested. Early user reviews are "very positive", and lots of players mention how relaxing they've found it.