As a gacha game coinsure, I'm extremely exited to share some recommendations. sorry if you weren't looking for gacha, I'm a loser and that's all I play. I also don't know exactly what ur looking for, but I hope there's something here!
Simple/not gacha:
Nyan Cat: lost in space. great use of my free time.
Gacha games:
(Strategy deck builder) Morimens: a horror game with great art and story. Essentially, you Get characters and build a team based off the cards that come with each of those characters, and build a strategy based on them and their domain. very fun, probably my current favorite game! also takes up minimal storage, all assets are 2d.
(Shooter) Nikke: Goddess of victory: great game if your okay with the extremely heavy fanservice and depressing storyline. Nikke is objectively a fanservice game, but all the character designs and story is well though out and the gameplay is very fun: just shoot and kill lol. the story is extremely depressing and has made me cry on occasion though, so keep that in mind.
Hoyoverse games, if you have the storage for it. I've played them all and personally my favorite is zenless zone zero.
(character builder) Umamusume: horse girl race game. you basically just build their stats. it can be played both casually and seriously! I'm a casual player, so I might not be the best person to recommend lol.
(Otome (I think?), fighter, decorator) Love and Deepspace: If you like romance, LADS is great! there's fighting mechanics similar to hoyo games (but not open world). My personal favorite part is the decorating; you can decorate a journal, photos with ur fav lad (my personal boyfriend is sylus), house decoration, and a whole desk! very fun.
(Tower defense) Arknights! I havent played it much. it was fun for what little i played, though!
There's definitely more but this response is already WAYAAAY Too long. I also gave an extremely brief overview of all these games and they all have a lot more gameplay then what i just said. hope there's smth you like!