You're definitely not alone. It's basically the same game as Brave Exvius and Record Keepers. In fact, you can trace the skeleton of this game as far back as Puzzle & Dragons. Maybe farther, but that's as far as I can recall. A ton of mobile games use parts of the skeleton(limited, renewable energy and whatnot), but this one uses pretty much the whole skeleton. It's just the skin(the graphics and, to some extent, how the player interacts with the underlying skeleton) that change.