Being required to perform repetitive and tedious tasks to advance.
"The more style challenges you complete, the more money and bonuses you can earn."
"Difficult levels may take several attempts; there is no way to skip them and go to more interesting puzzles."
"Increasing skills requires playing the same level over and over. (Combined with play-by-appointment - some levels won't be around later.)"
"especially during events, you have to repeatedly battle in raids with other players for limited rewards"
"One must buy machines in order to make items, and then make the items. Increasing storage particularly requires you to grind."
"Unless you pay, you need to do the same low level locations over and over in order to get materials to replace your gear. Because your gear breaks. Fast."