Aliens Invasion is a simple Android shoot-'em-up in which you must slay the extraterrestrial creatures that have invaded your world. You're equipped with only an axe and a pistol to begin with, although there's up to 12 weapons you can collect.
Each level follows the same theme: you start in the store, where you purchase ammo, weapons and extra lives to help you battle the aliens gathering outside. The shopkeeper is the only other human you'll meet during the game; the houses and pubs you pass on your travels afford you bonus cash and ammo, but no comrades in your quest.
Upon leaving the store you venture down a dark street, armed and ready to kill any aliens you meet. Sometimes they appear from the edge of the screen; other times they sprout up from the ground under your feet. If you're close enough you can crack them over the head with an axe or sledgehammer; from a distance, a shotgun or rifle is a better bet. Watch they don't corner you from all sides.
Three types of aliens haunt the streets: the purple alien is the first you'll see, and can be taken out by two shots to the face; the green alien walks fast, but dies quick; while the brown alien takes far more effort to kill. Every so often you get a boss level, where a huge green leg crashes down from the sky with the aim of crushing you under foot. You'll quickly learn to look out for the shadows forming on the ground, with your only challenge being able to escape fast enough.
A count is kept of your kills within each level, and you earn extra cash for each alien you slay. At first each level is incredibly easy, but they become harder to play as more and more enemies gang up on you at once. It's handy to have a pub or house nearby into which you can quickly duck until they've passed. Note that you can adjust the difficulty within the settings, but only before you begin a new game.
We got to level 38 using only one of our five lives, and you can always boost your health in the store. A health bar is shown above your head, with each alien bite gnawing away at its length.
Aliens Invasion supports multitouch, so it's possible to walk and shoot all at once. And the controls are simple: you just touch an onscreen icon for left, right, beat or fire. Tapping the ammo shown at top right cycles through your weapons, while a pause button is sited top left. We found a bug on our Samsung Galaxy Tab 10.1 whereby the game refused to display correctly when we resumed gameplay, frequently showing only half the screen.
Gameplay is open-ended, but there's nothing to aim for once you've collected all the weapons. We quickly tired of playing the same game over and over again in every level, with the only difference being the number of aliens homing in on us. You can't pick which level you play - you simply start afresh or resume an old game - but there's no reason why you should want to in any case. It'll take some time to earn enough cash for all 12 weapons, though, and in the meantime Aliens Invasion can become rather addictive.
The graphics are good on even a 10in screen, although things can become confusing once you've got an army of aliens surrounding you, plus rubble from where they've broken out the ground and the glistening carcasses of those with which you've already dealt.