Here is the full list of all 12 Catzilla - there are Advanced achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Your PC is Big Catzilla. You are the Champion!
Your PC is Mid Catzilla. You are the Champion!
Your PC is Little Kitty. Check recommendations how to get higher.
Your PC is Mid Kitty. Check recommendations how to get higher.
Your PC is Big Kitty. Check recommendations how to get higher.
Your PC is Little Cat. Check recommendations how to get higher.
Your PC is Mid Cat. Check recommendations how to get higher.
Your PC is Big Cat. Check recommendations how to get higher.
Your PC is Little Tiger, not bad.
Your PC is Mid Tiger, not bad.
Your PC is Big Tiger, pretty good.
Your PC is Little Catzilla, pretty good.