If you've not tried Gameloft's Dungeon Hunter franchise, it's definitely worth taking a look at. Dungeon Hunter 2 was the first in the series to be released on Android (and is still only available for select devices on the Gameloft store), and is genuinely one of the most fun titles I've played on mobile. Dungeon Hunter 3, though it went to a free-to-play model, was still extremely entertaining and undeniably well-done (4.5 stars with over 100,000 reviews on the Play Store).
The fourth incarnation of Gameloft's action-RPG Dungeon Hunter franchise is going to be coming out in the near future, but the developer is already priming the pump with a teaser trailer. Unlike some other pre-release trailers, this one actually includes gameplay footage. Take a gander.
It looks like the same kind of hack-and-slash gameplay from past editions of Dungeon Hunter at work here. There will still be an arena where you can do battle against other humans, but the main quest will surely be the meat of the experience.