Pretty much every game is iterative. Developers take ideas and concepts and add their own spin to them, moving the medium forward with every extra tweak.

Take Lightopus. To all intents and purposes it's a riff on Snake. You're a creature traversing a bordered world, gobbling up a coloured pellets until you've eaten enough to escape.

More than that, though, it's a neon-infused arcade gem, a retro-tinged wander through a spectacular underwater realm that falls just short of greatness.

Better down where it's wetter

You control the titular Lightopus - a glowing jellyfish with trailing tendrils and a bulbous head - either with a floating joystick or by swiping across the screen in the direction you want to move. It's your job to free tiny fish that have been trapped in shells by an evil monster.

Freeing the fish, or Bulbies, is as easy as moving through their spherical prison. Once they're liberated they'll follow you around, acting as a speed boost, a weapon, and the key to your escape. Deadly sea creatures chase you, but you can dispatch them with a well-timed flick of your mace-like tail.

Once you've collected enough Bulbies you'll be travelling fast enough to burst out of the confines of the level and move onto the next: of course, if you're a completist, you can stay and collect more of the fish, and the stars that each level contains.

Dreamscape

The Bulbies act as a shield against the nefarious creatures that swim around every level looking for trouble, and will sacrifice themselves to save your skin. If you lose too many of the little urchins, however, you won't be able to escape the level, and it's Game Over.

Collecting the stars in a level also has a dual purpose. If you gather the three on any given level, you'll get the highest score multiplier. Collect eight of each colour over your play time and you'll be transported to a bonus level where you attack the evil fish-snatching creature's eggs.

There's a dreaminess to Lightopus that sets it apart from other high score-chasers. Its characters drift rather than race. Its colours and soundtrack create an atmosphere that sedates, ultimately producing a relaxed, experimental experience rather than the trademarked clock-ticking panic game players are used to.

Beside the seaside

The slightly odd checkpoint system, which saves your progress every so often rather than after each level, is an annoying misstep, and the control systems aren't perfect either. But Lightopus has a unique aura that makes it eminently enjoyable.

It's take on Snake is an intriguing one, and the extra layers of gameplay and ideas make for a game that's unlike anything else you'll have played. Part Geometry Wars, part exploration, part adventure, and brimming with visual quirks.

The App Store gives games like Lightopus a home, and long may it continue to do so. This is innovative gaming at its finest, and whilst it's let down by a few niggles, they're not enough to spoil what is a fantastically enjoyable, highly playable arcade adventure.