Zombie-chaser is a graphic(al) interface to mutation testing. Mutation testing involves making modifications to software code, and seeing if the unit tests detect these changes and indicate a failure.
In the zombie-chaser gooey metaphor, mutated code is represented by zombies. Each successful test is represented as the zombies getting one step closer to you, and a failed unit test kills off the zombie. If you fail to kill the zombie, it gets to eat your brains.
This video shows what the program looks like.