If you're looking for a fun co-op game to play on the go, then you definitely must try out Dragon Dice. I have been spending most of my time playing this game because it's both challenging and fun. Don't expect to solo any of the bosses in this game as it's a party game. The auto party system is very useful, but doesn't work as planned. Don't bother looking at the game images shown below, I suggest jumping straight to the trailer.
Mini Game Guide and Starting Tips
It doesn't really matter what starting character you choose because the equipment obtained in this game changes your appearance. I suggest adding as many active friends as you can because they can automatically jump in on your boss battles and vice versa, if they are in the room as you. It's a good idea to upgrade your weapons even if it's just R grade because you can set it to your sub weapon later for bonus stats. When a weapon or armor reaches level 10, you can limit break it by paying gold and cubes. Once limit broken, you can grind another 10 levels rinse and repeat. Unlock Skills? You must unlock a skill slot on that certain weapon or armor by using the items that look like stamps. The success rate is very low, but once unlocked you can equip all kinds of skills which look like orbs with random swirls. My favorite one so far is heal because the bosses in this game hurts a lot. While fighting bosses, you can interrupt the attack by targeting the shining hit box. You can break off boss parts like arms, staves, gems, hats, reveal weak points, and etc. for more items. That's all I can think of for now, time to go back playing!
App Store: Link