The story follows Aztec emperor Montezuma's retreat to an otherwordly dimension due to the arrival of Spanish conquistadors. And seriously, when you choose to fight a realm of beasts like "Salamander XVI" in a game of wits instead of facing the conquistadors, you know they're a bunch of jerks. Montezuma's trip is temporary though, and each victory restores power that he'll eventually use to return home.
Aside from the story mode, there are tournament options for competitive multiplayer matches as well as an unlockable Endless mode. Bonuses and items can be purchased with Crystals, a currency that Montezuma: Arena awards for each battle, although there's also a store to buy Crystal with cash. Uh ... the legal kind of crystal, of course.