Portabliss: Tiny Invaders (iOS)

Did you know that you can download handheld games now? That's amazingly convenient! The only inconvenient part of it is finding the right games to buy -- and that's where we come in, with our Portabliss column. In each installment, we'll tell you about a downloadable game on the iPhone, iPad, Android device, DSi, 3DS, PSP, etc. Today: Tiny Invaders.

Contagion is a fitting topic for an iPhone game, considering how often I've picked one up after coming in contact with someone that already had it. And though Tiny Invaders isn't a deliberate metaphor for viral marketing, I'm happy to help spread its icky green tendrils.

First-time developer Hogrocket (which is basically cheating by employing Geometry Wars designer Stephen Cakebread) has created a fun little game about trains, and then hidden it inside a lighthearted tale of alien invasion. In order to take over the bodies of various American caricatures, you guide your microscopic, autonomous invaders through the bloodstream by tapping on turns and junctions to change their path. Once you've collected all the on-track orbs and carried them back to the originating ship, you move on to the next stage.

The top-down view and circuitous level designs make it apparent that you're really switching train tracks and rounding up cargo, which makes just a tad more sense than the alarming medical anomaly presented by a bunch of orbs in your arteries. But that's a question of presentation -- what matters is that it's a simple, easily decipherable mechanism. Tracing possible routes with your mind becomes reflexive after a while, and essential once Tiny Invaders starts stacking other ideas on top of it.

Timing becomes especially important, with a tap speeding up your invader train or the enemies hurtling through the same maze. It takes a keen sense of prediction to avoid criss-crossing collisions in the more complex levels, which also throw in teleporters, spirals and direction reversals. Your participation may seem indirect at first, as an unseen redirector, but full mental involvement is necessary if you aim to collect a three-star rating alongside those orbs.

You know what? Maybe they're undigested spheres of artificial sweetener. That could be it.

Tiny Invaders is available on iTunes for $3.99 for the iPhone -- but it's free for a limited time! We're always looking for new distractions. Want to submit your game for Portabliss consideration? You can reach us at portabliss aat joystiq dawt com.