Walk n' Play debuted this month on Apple’s "App Store" and can be downloaded for free by iPhone users. The game was devised by researchers at UH’s Computational Physiology Lab, led by Ioannis Pavlidis, the Eckhard Pfeiffer Professor of Computer Science.

The game lets users keep track of their physical activity through their iPhones. Just keep the iPhone in a pocket or carry it in a purse, and throughout the day the game’s cutting-edge calorie calculation technology records calories burned while walking.

Players can compete in real-time against another iPhone user or against a simulator and watch the calories burn off as they go about their everyday walking — like taking a brisk walk during lunch, climbing the stairs or walking the dog.

Pradeep Buddharaju, a post-doctoral researcher, and Yuichi Fujiki, a Ph.D. student, co-authored the game with Pavlidis.

Walk n’ Play is among the thousands of third-party applications that can be downloaded from the App Store. Anyone can design a program — such as a game or a news, entertainment or networking tool. If approved by Apple, the program is made available to iPhone users.

Within two weeks of its debut on the App Store more than 900 users from all over the world were playing Walk n’ Play, with about 60-70 new users joining each day, according to Pavlidis.

Last fall, Pavlidis and Buddharaju taught a new class where computer science students get hands-on experience designing software applications for the iPhone.