Hard pick because I listen to a game or series for a while, then another. Just today I went and listened to a lot of Sonic tracks, which I do once every few months. I guess Atlus games (SMT, Persona, EO), Metal Gear Rising, Ace Attorney, TWEWY are in the lead off the top of my head, but after a month I might give a different answer. My relaxing music playlist is mostly the official classical arrangements of Etrian Odyssey 1+2, so let’s go with that.
Started Trauma Center 2 and 7th Dragon 2020, both sequels to games I played last year. The first one I only played for 10-20 minutes so far though, the latter would probably be unbearable without turbo mode via emulation. Actually, 7th Dragon DS already was, but the story and setting is mildly neat, and I might be hungry for games with more party building. If you fast forward to the dragon/boss fights it’s alright.