>>66102716I could unironically write a whole paper about this game but I'll do my best to give you a TL;DR.
On it's surface it's a procedurally animated survival exploration platformer. Look a little deeper and you'll find the game has an developed ecosystem and is littered with esoteric mechanics that add an in a layer of depth that I've never really seen before in a platformer. The best part is none of those mechanics are locked behind levels, power-ups, or progression. Everything is available to you from the moment you start, it's up to you to learn and figure it out. The story and lore are mostly secondary and there isn't much difference between the main three choices of survivors. A few years later Down Pour comes out and it is the best bang for your buck expansion DLC I have ever seen. It adds 5 new survivors each with different mechanics all taking place at different time periods in the lore and thus having unique campaigns. There's new areas to explore, additions to the ecosystem, and the game is given a full blown story that really knows how to punch you in the gut towards the end. Be warned, the game is hard and only gets harder in each subsequent campaign so it won't be for everybody but if you can find enjoyment in that you're in for one of the most rewarding gaming experiences in a long time.
Long story short Base Game is good, Base Game + Expansion is Outer Wilds tier. It isn't cheap so watch somebody else play it for a bit first to see if you'll like it.