"Ow! Get off my head!" Topple's amusingly expressive blocks just add to its charm.

If Tetris and Jenga ever, um, did it, their offspring would look a lot like Topple. The game combines colorful, uniquely shaped blocks (there’s your Tetris DNA) and whoa!, whoa! stacking (all Jenga). Oh, and because this unholy union defies various laws of nature, all the blocks have faces. It's weird, yeah, but cute and ridiculously fun to play.

In the game, a block starts out at the top of screen. You drag it to a spot on the bottom, rotating it via two-fingered multi-touch, if necessary. Your goal is to build a balanced tower that reaches a specified height without tipping over. If a block doesn't fit your stacking plan, you can fling it off into oblivion, though if you lose or fling four blocks, you lose the game.

So where’s the challenge? As with Jenga, the higher you build your tower, the more it teeters. And the oddly shaped blocks hinder stability. As you progress through the levels, the goal line gets higher and higher. And soon you start with a base that isn't even flat. Plus, there’s a time limit.

The game is tilt-sensitive, meaning you can tip your iPhone left and right to try to keep your tower standing. Eventually it’ll start to fall apart, resulting in a mad, stacking dash as you try to reach the goal line. A bonus line even higher adds extra challenge and points.The animated blocks bring the game to life, with them smiling or wincing as you stack. Topple accomplishes an awful lot of cutesy with nothing more than eyes and mouths. The circus-style background music adds even more to the game’s cartoonish flavor.

Except for a couple minor gripes, like a buggy pause button and training levels that don’t fully explain the game, Topple is a blast.