Epic's ChAIR Entertainment created Infinity Blade, the game that brought the Unreal Engine to iPhone and iPad, in five short months. That revelation came from studio co-founder Donald Mustard as part of his "Infinity Blade: How we made a hit, what we learned, and why you can do it to" post-mortem talk at GDC 2011

Infinity Blade, in fact, was not what they had been planning to work on next. After finishing Shadow Complex, the studio went into an intense brainstorming mode where over a two-week period each member of the team took one day and presented 30 game ideas. From that they narrowed down to a list of 20 for which they would do one-sheet design documents. Then Epic called.

Unbeknownst to anyone, a segment of the Unreal Engine team had been hard at work on mobile, and Epic wanted a game to showcase it. The call came in June; they wanted the game that fall. With a short development window, the team had tough choices to make. They decided that visuals would be the hook--the thing that would get someone to look at the game more than once. To make it look the way they wanted, though, that meant they had to limit what they put in the game.

It worked because they matched it with the unique catch of sword fighting. Mustard described the vision for the game as a combination of the fighting action of Jordan Mechner's Karateka with the dramatic impact of Shadow of the Colossus. They quickly got an animated prototype going and felt they had the core fun right of using your finger to swipe like a sword across the screen to meet an enemy's attack. Everything then worked to support that nuclues. For instance, the movement system wasn't limited by the system. The designers made a conscious decision to use touch movement because bringing up virtual sticks to control moving around would have introduced a whole new control scheme and disrupted the cinematic mood.

Attention also went into making the game play right for the mobile platform and keeping the player coming back. Mustard said that one of their "pocket pillars" was that the game must be playable in a meaningful way in two-minute bursts. This accommodates the "truth" he said we must accept that people play these games on the toilet. In fact, took into account how long one could sit there and play before their legs started to go numb.

Another of those pillars supported keeping players coming back to the game. They wanted the game to be truly skill-based, something players could get better at by playing more. And though the game hands out improved weapons, that system is more a mechanism to keep players encouraged as they learn to play better. By the time a player beats the game, it's more a result of their improved skill than any new items.

And if you mastered those skills, there's more challenges coming soon to Infinity Blade. Mustard shared that they have a major content patch mostly complete that should be out shortly.