There was a time not too long ago when the prospect of bringing a game from the PC to a mobile device was inevitable disaster. The iPad, however, has managed to prove that it can not only match the quality of an original PC game, but at times it can best it, offering a better play experience with a touch screen than a mouse and keyboard could ever muster. Past examples include "Plants vs. Zombies," "World of Goo" and "Osmos," all of which were considerably more enjoyable on the iPad. Now joining that delightful crew is "Anomaly Warzone Earth HD."

The marketing-speak description of "Anomaly Warzone Earth" is "reverse tower defense." In practice, that means you're controlling the creep, rather than the towers. In this case, the creep is a series of military vehicles making their way through an alien-infested city. You can check out an overhead map of the city, selecting the route your creep will take based on the towers placed along the sides of the roads. You can also boost your creep with money, improving stats and adding to your number of units.

The objectives vary from mission to mission, but it's usually as simple as "Destroy these towers" or "Get to this point."

So why is it so much better on iPad? It's all about the simplicity. The original PC version had you controlling a commander who ran around your vehicles on foot, repairing, dropping smoke grenades, so on and so forth. In addition to keeping an eye on your creep, you had to keep your commander moving alongside all the action. It was a lot to keep track of, especially for fans of tower defense who usually don't have to worry about things like moving units around.

On the iPad, the commander is gone, perhaps felled by some unfortunate incident with a tank tread. In his place is your finger, which can drop power-ups and airdops anywhere on the battlefield. It's incredibly intuitive and the game's learning curve ramps up nicely, introducing new elements and variables at a manageable rate.

Granted, the iPad version of "Anomaly Warzone Earth" isn't quite as pretty as the original PC version, graphics-wise, but it's still a remarkably detailed battlefield that's both pretty to look at and tremendously functional.

If you're in the more casual "Plants vs. Zombies" crowd, you'll probably find "Anomaly Warzone Earth" a bit daunting, even on the easiest difficulty setting, but more hardcore gamers should definitely give this one a download. It's one of the best games the iPad has to offer.

Note: "Anomaly Warzone Earth HD" is the iPad version of the game. There's also an iPhone/iPod Touch version, which is called simply "Anomaly Warzone Earth." If you're deciding between the two platforms, I'd suggest going with the HD version. The increased screen real estate makes a big difference when it comes to tactically placing upgrades and guiding your creep.