PzzApp is a simple 15-puzzle game written in Cocoa in a 2 day hackathon with Ana Cañizares as our first (and only) program in this language. It is far from being finished but usable. It's also quite pointless in itself.
You'll need a working installation of XCode and MacOSX >= 10.6. Open the project file, set the base SDK to whatever you have and build.
Use at your own risk. Your computer may freeze due to boredom. If it does you can drop me a line at m DOT debenito DOT d AT gmail DOT com.