I played this while there were two collaborations with other games. The amount of money you'd have to spend to get your collaborated characters up to maxed out stats takes away some of the fun because you truly have to grind. The gameplay itself is fun, and the story is okay. The summon percentages don't seem to make any sense because it will sometimes take 20 pulls for a UR collaboration character and sometimes less. I enjoy playing casually, but I am frustrated by the apparent greed.