Previously a Flash game, Hundreds has been ported to iOS with great success, incorporating intuitive multi-touch controls.
The idea is to tap a series of circles on the screen. With each tap, the number on the circle increases, until it reaches 100. As they grow, circles turn red, and if they collide, the game will end. Each level incorporates new challenges and gameplay elements. From the App Store description:
Simple in concept, deep in design, Hundreds is a puzzle game that requires quick fingers and deep thinking.
The goal of Hundreds: Grow at least 100 points between the circles in each puzzle. Circles turn red and volatile while being grown and if they collide, it's game over. It's that easy.
Hundreds can be downloaded from the App Store for $2.99. [Direct Link]
Article Link: 'Canabalt' Creator Releases Minimalistic Puzzler 'Hundreds'