Just click the cat, and a random number will be generated to see if you can get the next cat! There are 16 cats so far. You can't auto-click/spam-click, I'm still figuring it out. Clicks may be inconsistent.
Update Log: Version 1.0: Release! Version 1.1.2: Bug fixes, added one more rarity. Version 1.1.8: Remade sprites. Version 1.2.1: Tweaked some sprites and added two more rarities.