It's nintendo's recently released mobile game, in which players can control fire emblem characters from different games in the series. You fight against the emblien empire who "wishes to rule all worlds". I'm terrible at explaining things so I'll just let the site do it. https://fire-emblem-heroes.com/en/sp/ It's actually pretty good, IMO. It's a bit lacking at the moment, but they plan to add content (chapters, characters,etc) every month or 2 weeks apparently. There's also the whole "stamina" thing. It's a free to play, so there are micro transactions. But it's nothing that can't be earned in game easily. Gems are easily earned. You get 1 per chapter. They can be used to summon heroes. The cost for summoning heroes decreases if you're summoning multiple in a single "session". Tip if you're just starting out. If you want to re-roll for better heroes at the start don't link a Nintendo account, and complete the first 3 missions, and collect your log in bonus. Doing so gets you 20 gems, which is the exact amount you'll need to summon 5 heroes (the max that can be summoned in a single session). Anyway, it's a pretty good game so far and it might be worth your time if you're a fan of the games or just looking for a good mobile strategy game that ISNT another damn candy crush clone (or vague game of war ripoff)