I've been hooked on Vampire Survivors because of how unobtrusive the ads are. They're completely voluntary and not required to get the full game experience at all. I've done most of what you can do and found Magic Survival to be another good survivors game. The ads aren't optional, but they only occur at the end of a run, so it's really not a big deal. It's a bit more primitive than VS, but the game play loop is still there and engaging.