I'll drop mini-reviews of what I've played in the comments. Still, this challenge meant I played some amazing things that would have otherwise stayed ignored in my library, and I'm grateful for that. This is a bit of a mixture, mostly fairly quick indie titles, but not all (looking at you Stardew and Tropico). I have 360 games, so 36 meets the target. I don't have as much time as I might like to play, so I set myself the goal of getting to the point where I'd 100%-ed 10% of the games in my library (one or two I managed last year).
I've got into achievement hunting this year, mostly as a way to encourage myself to work my way through my existing Steam Library rather than buying new games.