How do you follow a game like Scribblenauts, in which you can make and do almost anything? For developer 5th Cell, the answer is to make a game in which you can only do one thing: jump.

Run Roo Run for iPhone and iPad, coming this Thursday, is a "micro-platformer" about a kangaroo crossing the suspiciously dangerous landscape of Australia in search of her joey. We've got the first media, along with details from 5th Cell. Run Roo Run is an "auto-run" game in which you tap to jump, sort of like Canabalt -- but set in a series of predesigned, increasingly complex levels instead of a never-ending randomly generated world. This is the "micro" aspect of the "micro-platformer." "That means every level, from start to finish, is just a single screen wide," creative director Jeremiah Slaczka told Joystiq. "Typically, auto-runners don't have levels, you just travel as far as you can until you die."

Roo, on the other hand, has a set of 420 levels divided into chapters, each introducing a new element, like double-jump items, fans, retracting spikes, and crumbling aerial platforms. Each jump is accompanied by the placement of an arrow, allowing the player to see exactly where he or she took off from, in order to correct fatal errors in the next attempt.

In order to serve both casual, Angry Birds-type players and platformer superfans, Roo's levels are divided into "normal" and "extreme." "Players unlock the extreme levels of each chapter after beating the normal ones," Slaczka explained, "but you can completely bypass the extreme levels and just focus on the normal levels if you want. I wanted to make sure both casual players and core gamers had content to enjoy."

Those 420 levels will be augmented by a weekly release of 10 levels, for free -- a delivery that "won't require a product update," Slaczka noted.

Fitting with the bite-size nature of iPhone games, this is a smaller-scale project than 5th Cell's previous works. But it was almost even smaller. "The idea had been gnawing at the back of my skull for a few months," Slaczka said. "The simplicity of the base concept was a very compelling idea. So one Saturday afternoon I decided to sit down and write out a two page design doc. I showed it to our Technical Director and co-founder Marius Fahlbusch and we began working on the title after core work hours." The game was originally set to be developed within six weeks, but the team kept working on it until it became a "full-time project," with development spanning another three months."We brought in one of our artists and a level designer and rounded it out with our sound team and voila! A game!"

The inspiration for Roo's trip comes from a Flash game by Chris Jeff called Space is Key, a much more abstract experience about navigating ever-changing landscapes with only a jump button. "It's been kind of a weird experience for me," Slaczka said. "I haven't been so directly inspired by a title in years. In my previous titles Drawn to Life, Scribblenauts or even our upcoming shooter Hybrid, they were so unique that they were only loosely inspired by other concepts at best. But with Run Roo Run it's been fun to get initial inspiration from another title, adopt it and morph it into something all your own."

For 5th Cell, an original mobile game is something of a reunion. "In 2003 we started out as a mobile game studio with ambitions to break out and do bigger games," Slaczka said. "The mobile market back then was like the Dark Ages compared to today." The developer fled (pre-smartphone) mobile development for the Nintendo DS, where it found success. "The market has changed a lot since then," Slaczka said, "and Apple has done a great job in raising the bar for how mobile content is developed and consumed. We felt our efforts spent making a new mobile IP would be worthwhile."

This article was originally published on Joystiq.