Oddballz
Your Wacky Computer Petz

Stat Changes:
Go to the folder where you have installed Oddballz. (usually C:\ODDBALLZ) then go into the folder EGGS and open the folder of the species of the oddball you want to change. The click on the icon in the folder that looks like a notepad icon with a yellow gear on it. You can change a bunch of stuff like age, fleas and happiness.

A more detailed description can be found here