Aloof

Very fun little puzzle game that can post a surprising challenge in the later levels, depending on the difficulty you choose. I played the campaign with a friend and we had turned the difficulty up at first because we thought the game would be easy, but then had to turn it back down after getting humbled later on.
At first glance I thought that the game was basically "Tetris where you can freely move falling pieces", which seemed like it would be way too simple to beat, but there's a surprising variety of win conditions. I especially loved the "puzzle" levels. Rather than giving you a tutorial pop-up to teach you about some advanced mechanic, the game would give you a puzzle where the only possible solution would be for you to figure the mechanic out on your own. We always felt like geniuses when we'd finally figure out what the game was trying to coax us into learning, which is how a good puzzle game should make you feel. The co-op is also well integrated into the gameplay--it's not like you're just quietly playing side-by-side for 2x the points. You want to talk to your partner so that you're building different shapes, or healing effectively, or sending combos at the same time, etc.
It took us 5-6 hours to beat the main campaign (some of that time was in steam remote play, so it's not recorded on my playtime). That's worth the full price to me. The only snag we hit was that we couldn't join each other's lobbies the first time we played, which is why we had to remote play at first. We didn't have that issue again, though. I'm honestly surprised at how little exposure this game seems to have had, since it feels like it should have pretty mass appeal in the cozy puzzle genre (especially with co-op). It's definitely worth checking out.