you start off with 3 guaranteed 5* which are the same for everyone no matter how many times you reset account. Note you can still get regular units as 5*'s so don't get excited when you see a gold. The gameplay basically is just auto attacks and just you building a team and upgrade their equipment/find some better ones or evolve the unit's and level them. However it pretty much just became a waiting game once you clear chapter 3 i guess. The reason being is once you get there your progression gets hault for a while since can't really repeat a stage to grind currency towards leveling unit's since enemies still get tougher. The only method to grind is to wait for the mines to reset which what makes the game more of an idel type game.
it works for what it is but was really hoping it wouldn't be idel and have the auto attacks/specials be a thing. It is very f2p since it gives you methods to acquire random 5* and 4* and selling 3* to buy shard to summon a 5* or 4* randomly ofc. In any case do with that what you will it was fun till i found out it was auto attacks tho but maybe it'll be a game for you if your busy. also gl with the same battle music.