Cheat Engine for Mac is an unofficial port of Cheat Engine for Windows.
The aim of Cheat Engine is to enable you to modify single player games running in Windows to make them harder or easier depending on your preference. It also contains a few other useful tools to help debug games. Cheat Engine for Mac also includes a memory scanner to check for variables within a game and also includes a few other tools such as a disassembler, trainer maker and direct 3D manipulation tools.
However, its very hard to understand exactly how to use Cheat Engine. It definitely does not work with the forthcoming OS X 10.8 Mountain Lion and is problematic in Lion. It isn't a very well maintained project so there is little hope a working update.
Cheat Engine for Mac is a dated utility that will only work on older versions of OS X. It's recommended that you use Cheat Engine for Windows.