A lot or a little?
Parents need to know that Mana Monsters is a fighting-focused game for iOS and Android devices. The one-on-one attacks involve creatures, not people, and aren't gory. Although some aspects of the game can be a little confusing, due in part to the number of items players can get as rewards and use in various ways, the developers have made a notable effort to offer ongoing explanation from characters. Players get some additional help during games, such as suggestions for the best team for a match. You don't have to buy anything to play, although you may be interested in purchasing crystals because they aren't awarded as often as other items, such as coins, and can be used to avoid gameplay slowing down or stopping. Otherwise, there's no inappropriate content in the game.