One of the App Store's earliest original sensations returns in Fieldrunners 2, a sequel to the tower defense affair in which you'll place towers across various open battlefields to repel the coming forces. Much like in the original, the myriad Gatling guns and missile turrets can typically be placed in dozens of locations, letting you concoct winding mazes to direct the enemy grunts and tanks through, and it adds an extra layer of strategy to consider as you aim to protect your base.

Fieldrunners 2 shakes things up with more terrain variety, such as tunnels and tight paths that you'll need to work with (or around), plus additional play variations that eschew the typical enemy waves for all-out assaults that give you a death tally to hit, or offer limited resources for a more puzzle-centric affair. But the core stages are still all about outlasting the enemy through prolonged battles, as you upgrade and expand your arsenal to take down the aggressive foes.

While the familiar cartoon-like aesthetic from the original returns, it looks markedly better on the second go-round, with impressive detail and animations, plus a gorgeous map screen that lets you bounce between challenges. There's plenty here to see and play, though the sudden difficulty bumps can be frustrating, even on the lowest setting, and the lengthier missions seem to drag on just a bit too long in some cases.

The bottom line. Fieldrunners 2 may up your ire more than expected at times, but it's another slick, action-packed affair that can keep you playing for ages.