Lot of odd “this is fun for a couple hours, then it gets too hard unless you pay, it isn’t even grindy” reviews for this game. Have been playing a week, haven’t bought a thing. Still progressing. Can only assume these people always play the single best line on the puzzle every time & don’t realize this isn’t always ideal because of how the battles are structured.
Be aware, you must keep your challenge level, damage level & health level at basically the same number to progress smoothly. Don’t let them get out of sync. If your challenge level outstrips the other two, you will eventually plateau & have to grind really hard to even them out so you can again progress quickly.
4/5 because (a) way too complicated, as almost all games are these days, with the number of distinct currencies to collect & use (b) it is too easy for the game to goad you into spending money by creating artificial obstacles. The “random” fall of the pieces in the puzzle can cause you to easily lose a battle you were way ahead on. But again, this is not uncommon for these kinds of games these days.