It's a Attack On Titans rip-off with a Story Mode, and some Trials that offer to test your mettle. There's also a mode which you fight until you die called Extinction and Skirmish which allows you to customize your own scenarios that can be shared amongst your friends. Daily Challenges also allow you to see who's the best Sentinel of the day. No matter which mode you choose, they're all a little too repetitive to hold your attention for very long.