Match-three marble shooters such as Zuma and Puzz Loop are hardly unique on the App Store, but we can guarantee that you've never experienced one quite as twisted as Eyelord.

Created by Secret Exit, the team behind Zen Bound - which is about as far removed stylistically from this latest effort as you could possibly get - Eyelord is your basic marble shooter but with a grisly difference: instead of shiny orbs, it features soft, goo-covered eyeballs. Needless to say, it's not for the squeamish.

As is standard practice in this kind of caper, the balls roll along a set pathway. If they reach the end of said pathway - in this case, the mouth of a manic heavy metal skeleton - then it's the end of your game.

You remove the balls by tapping where you'd like the next randomly selected ball to go. This is the game's other major change from the accepted marble shooter template - you don't actually shoot the balls, but simply place them with your finger.

An eye for an eye

Match three or more balls and they'll be removed from play, adding to your points tally and giving you some more breathing space. When a group of balls is removed, leaving matching balls in their wake, these will be magically attracted to one another, pulling the line backwards and giving you even more room to play with.

Eyelord also features special one-shot 'Boost Gear', which you can buy from the in-game shop. These make things a little more bearable, but it's a better idea to save up the cash you earn for unlocking more potent bonus items, which are randomly injected into the line and allow you to perform tasks such as freezing time or blowing up a large section of balls.

And here I'll remind you that when I say 'balls', I mean 'eyes'.

Someone at Secret Exit is clearly a massive fan of '80s metal, as Eyelord looks and sounds like the kind of iPhone app that Iron Maiden would cook up if they were 30 years younger and skilled at iOS development.

The soundtrack is full-on poodle-perm rock, and the gloriously sharp and detailed visuals both delight and disgust in equal measure - the sight of several eyeballs popping in unison is wonderfully toe-curling, especially when accompanied by the tremendously unsettling sound effect.

Eye eye, captain

Although Eyelord features in-app purchases and is available to download for nothing, it doesn't push the freemium card too strongly - in fact, you're likely to have a more enjoyable time if you avoid the urge to reach for your credit card.

Because Eyelord is effectively just one game mode, the motivation to keep playing is based around improving your score and unlocking all of the items. The in-app purchase option effectively robs you of that second quest, as it makes it easier to unlock everything from the start.

Eyelord could never be described as a conventional video game, but its unique approach breathes new life into a well-known - and possibly tired - genre.

The presentation is outstanding, the gameplay is immediately gripping, and the drip-feed of unlockable content perfectly pitched. Even if it didn't come as a free download, it would still be highly recommended.