Humans vs Aliens is no Plants vs. Zombies, but until the popular iOS game comes to Android, this substitute will fill the void in the meantime.
The game's format and concept are the same as Zombies, but in Humans vs Aliens, you're fighting off a slow marching army of aliens instead of a band of the undead. To play, you have to keep these creatures out of your cities by strategically placing your special skills and forces on the map.
When you start, you'll only be given a handful of ways that you can fight off the aliens, including a couple of silly weapons, like a pitchfork-toting, drunk redneck. The more you play and advance in the game, however, you'll be handed much more helpful, powerful reinforcements, like snipers, helicopters and snipers. Of course, as your weapons become more advanced, so do the monsters you're fighting.
The real challenge of the game isn't necessarily the fact that you need to fight off these aliens, but that you are only given so much energy at one time. The more advanced, efficient attacks require more energy and mean that you can't bounce back as quickly to fire more attacks. That means you may spend some time twiddling your thumbs, panicking as you wait for more blobs of energy to appear on your screen.
While I welcome the strategic challenge (it makes the game more interesting and fun), there also seem to be some flaws with timing that makes things frustrating. There seem to be more aliens than there is energy and so it's sometimes pretty impossible to keep up with the attacks.
The fact that you are constantly being handed new weapons and different kinds of aliens, but the game doesn't seem to evolve at all. Because the game's pretty repetitive and the fact that there are some hiccups with the game's energy programming, Humans vs Aliens may not hold your attention for very long.