It was easy to play, no intro?, and so simple. But in the battlefield, my heroes are also random style of attacking, and I'd realised that heroes have a charged skill (simple put, it's a ultimate skill).
If you hit them, there's a combos each of my heroes attacks. It's level is limited at stage 8 and that's the end, how simple it is.
There's no exit button for sure, but I'm satisfied that this game is so simple..