I know you mentioned the sequel, but have you also played the original Risk of Rain? I just ask because I got them both recently and I've been enjoying them.
Also, just FYI, if you're really liking the RoR2 early access soundtrack, you should buy it on Bandcamp like immediately. The author posted a notice that it was about the last month to do so around a month ago. It also comes with 50% discount codes for the original's soundtrack and the Engineer editions, when you get them the codes technically mention they're expired but I think they were extended since it took longer for the game/OST to be completed than they were expecting because I used my RoR1 code when I bought them yesterday.