Click the cat and use upgrades to increase your score. Watch out for the gold cat and it will increase your score by 50%.
Thanks to @ShiftClickLearn for an idea I couldn't do. Thanks to @Electricbulb_ for visual effects Rebirthing gets you a new costume up till Rebirth 11 0. Normal 1. Blue 2. Green 3. Pink 4. Anti 5. Rainbow 6. Zombie 7. Gold 8. Retro 9. Sad 10. King 11. Rainbow King
