Invaders

The celebrated arcade sensation gets yet another clone - this time without the "Space" in its title, since instead of marauding aliens we're dealing with mere earthly bugs. Waves of well-regimented insects are on the attack, and the only defense is a lonely, laterally-moving tank, which must dispatch the flying formations before they hit the ground.

Naturally, the vermin shoot back. A series of shields provides a limited form of cover, though they can be damaged by fire from both directions (and if the enemies manage to swoop down low enough, they'll gnaw their way right through this scant protection). Most perilous are the ticks, armed with indestructible missiles that pack a bigger punch. For bonus points, you may hit the occasional rat that scampers across the top of the screen - just make sure to aim for the body, since the tail is (somehow) bulletproof.

The starting wave and skill level are selectable: higher combinations will make the enemies more trigger-happy, start them off at a lower altitude, and shave precious pixels off the shields... or even join them into a single, solid barrier.