Haven’t played observer, but the aesthetic and horror aspect remind me of SOMA.
If you want something more action focused with a cyberpunk aesthetic, I can’t recommend Distance enough. (If you need a pitch: racing game with horror and your car can fly). I also just started playing Severed Steel and I’m enjoying it a lot so far.
I will also concur with the other person who recommended Outer Wilds. Don’t look up anything about it, go in as blind as possible, and try to see it through to the end. You will not regret it.