>>714604610You can see an average gacha as a weird combination of three genres.
VN that tells the story about whatever is happening in the game but doesn't really impact it in any way, and by the rule of live service it can never have a proper conclusion. They also tend to be painfully heavy on dialogues about nothing in particular.
Idle game, since pretty much everything in gacha is timegated in some form, and most of the activities in it are about gathering resources, it can quickly turn into open game->do chores->close game routine.
And lastly, the gameplay part. Usually consists of short, same-ish levels with continuously increasing enemy stats. 99% of your success depends on how much stats you have, meaning if you want to progress, you have to constantly do the chores and/or have strong units.
tl;dr Imagine Diablo 2 but it's only Baal runs and you can only do a run a day