Hooked

It's hard to explain how to describe it, but it's a gun action game that's also an idle育成 game. The more the cats shooting guns grow, the more exhilarating it gets, and the guns you use can also be leveled up. There are various events, and you can easily increase the diamonds needed for gacha like guns. If you watch ads, they double, so it's not a pain to watch ads voluntarily. There are no ads during gameplay, so there's no stress. (There are ads, but you don't need to watch them other than the voluntary ones mentioned above.) It's simple, but I think it's a fun game so far.