Hero Academy is a fun and addictive fantasy-themed combat-strategy game in which you play short, asynchronous turns against friends (through GameCenter or Facebook) or randomly matched opponents.
Each game is a face-off between two teams trying to advance and destroy the other team's fragile "crystals," with combatants moving horizontally or vertically across a small, chessboard-style grid. You have a "hand" of six tiles that you draw from a limited deck -- including new units, such as knights and wizards, and temporary and permanent power-ups, such as shields and healing potions. Each turn, you have to make the most of just five moves, each of which you can use to deploy a new unit, take an action for a unit (such as moving, attacking, or healing), or play a power-up from your hand. Do you advance your wizard to take advantage of a clump of enemies with a well-timed chain lightning? Or do you move your healer up so she's in a better position to help your vulnerable knight? Once you're done, you submit your turn to your opponent and then wait (maybe minutes, maybe days, depending on their punctuality) for a push notification to see what they do in response -- and since you can undo your moves before you submit your turn, you can experiment with different feints and sorties.
The games comes with the straightforward Council team, but other teams with different strengths and weaknesses--currently the explosive-friendly Dwarves, life-leeching Dark Elves, and orc-like Tribe--are available as in-app purchases. Buying these teams adds a new level of strategy to the game, as you adapt to different match-ups, and (perhaps more importantly) it also removes the game's relentless ads.
While it's a small thing, it's nonetheless irritating: sometimes loading the game can lock it up and you'll often need to reload games to take your term. This is something I think will likely be fixed in coming updates, but it's worthy of note.
Hero Academy's asynchronous turns can take some getting used to (there's no solo mode to practice against an AI), but the fast pick-up-and-play turns and the addictive quality of juggling multiple match-ups at once makes this game a must for turn-based strategy fans.