It's easy to get caught up in the hype of the recent Marvel films in the lead up to the eventual cinematic version of the Avengers. While the inevitable game conversions of said movies have been less than stellar, the iOS titles have been more than playable, showing some passion for the franchise it represents. Captain America: Sentinel of Liberty by Marvel Entertainment and Sarbakan mixes things up from the expected 3D beat'em-up by giving 'Cap' a free-running experience governed almost entirely by gesture-based inputs.

When talking about video games and free-running, one of the first games that pops in to mind is Mirror's Edge. Sentinel of Liberty bears a striking resemblance to EA's iOS conversion of Mirror's Edge, with Captain America running back and forth along a 2.5D world, springing up walls, flinging himself across gaps thanks to handy poles and running across long gaps thanks to the physics-defying wall-run. Intuitive gestures make it easy to get Cap moving in the right direction, with upward swipes causing him to jump, downward swipes causing him to slide and swiping towards an enemy to dish out a serving of fists and a boot or two. Combination attacks slowly unlock over the course of the game, slowing down the game after you initiate the maneuver via one of several entry points (either sliding, stunning and so on).

Once you're comfortable with the idea of swiping to get actions done, the game becomes much easier to enjoy, with enemies falling to the wayside as you scour the level for secret documents to unlock new skins and comic covers. Environmental hazards such as traps and trip-wires do add some challenge to what is an otherwise casual experience, but if you follow some simple rules (such as 'always take the upper path' and 'ignore enemies where you can') you'll finish the game with little effort at all. While it can be worth attempting to find hidden documents, exploring every nook and cranny can become a chore and trying to mix things up by beating up enemies also becomes tiresome thanks to the simplicity with which they're dispatched.

One really odd problem that kept cropping up as well was the way in which the game sounds would stretch out in sync with the current game speed, producing some rather unexpected and disturbing changes in the voice of Captain America. It only served to highlight some of the performance issues as some sections of the game would briefly stutter and then be followed up by a deep-throated Cap, only for the next line to be higher in pitch as the game speeds up.

It can be easy to be harsh on a game because it's deserving of ire, but in the case of Captain America: Sentinel of Liberty the disappointment comes from a decent concept being executed in a sub-par manner. If you enjoyed Mirror's Edge for iOS or you're a fan of the comics, there's more than enough to chew on here, but if repetitive action and the lack of scaling difficulty gets you down, it's best to leave this title alone.