Change is Good:
Make your own mouse or cat go to Lets Make a Character mode then make your drawing. Make sure you fill up all of the boxes then save it put in section one, two, three, or four then go to options then go to set up. Now for character it will say normal 1 2 3 4. Put the # of the section you put it in then they will change.

Make the Cat Blow Up:
It's easy just make sure that the cat keeps on eating then it will get big after a few more mice it will blow up.

Hard Mode:
Beat all normal stages in puzzle mode to unlock the hard puzzles in 1P puzzle mode.

Special Mode:
Beat the hard puzzles to unlock the special puzzles in 1P puzzle mode.

Mania Mode:
Beat the special puzzles to unlock mania mode in 1P puzzle mode.

Faster Credits:
Hold B to make the credits scroll faste.

Talking Cat:
If you turn on the game and don't press start for 3 hours (on title screen) then the cat will tell you to hurry and cry.

Thanks to Revolution readers Golden Midge, cary-wong-69 and Andy!