Update 1
At this moment game have 5 cats:
default cat(default button image won't drop)
alpha cat 40% chance drop, beta cat 40% chance drop, orange cat 15% chance drop, gray cat 5% chance drop
I plan to add 2 more cats at the game release it will be supporter cat that will be available in shop to support game development and “first cat” cat will drop for the first week after game release
Achievements will be in game
At that point I think that upgrading each upgrade will give u achievement + if u get all upgrade achievement for that. Of course simple achievements like get 1 cat or 1 million cats will be in game as well