Gameplay-wise it's almost a sort of casual pocket Diablo. Players tap to move about game levels, tap to target enemies with automatic attacks, and swipe or tap in order to activate special attacks. Rounds start off with the player being teamed with three other players, with level-end rewards for the most damage done.
DeNA is the company Nintendo has teamed up with to provide the mobile back-end to its upcoming mobile titles, so if you want a glimpse at the sort of monetization that partnership might have in store, look no further. In classic DeNA style, players can use in-game cash either earned through play or purchased in bulk to unlock rare and powerful characters. The more powerful the character, the more likely you'll be seeing those big level-end rewards.
I dropped a fiver on the free-to-play game, which scored me Ultimate Falcon and Nova via special recruitment, while the normal free recruitment got me lousy one-star Nick Fury. Hmph.
There's a bunch of story content available at launch, with special events starting right off the bat with an Infinity tie-in featuring the Avengers and the Guardians of the Galaxy versus Thanos, the Freshmaker.
It's not a bad little game so far, but the urge to put down cash for better characters is strong. Play at your own risk.