I'm confused, it looks like he plays 90% Minecraft and KSP?
I agree in principle though - I usually search on YT for reviews and/or gameplay before I buy anything these days, since gameplay trailers are like Hollywood movie trailers: they either give too many spoilers and/or they trick you into buying something that isn't what I want.
Check out the playlists, he's done a number of games. I have the Outer Wilds on in the background. (very cool game play)
Oliver is not a streamer I get recommendations from, he gets recommendations from his followers. I watch him more for the blind playthroughs of my more favorite games.
I've used some genre top lists YT videos lately