As noted by stardustsunday, you must first start up the game before following this tutorial:
"You have to install the game, open it, then play through a bit (just complete the tutorial and play for a bit more after that)."

Open up the registry editor using win key + r, then type "regedit".

Go to \HEY_CURRENT_USER\Software\Sergej110\Crazy Alien

OR

Press crtl+f, or go into the menu ->edit->find
Search for "Crazy Alien" or "TotalAnimal_h4239418657"

Edit the value of "TotalAnimal_h4239418657" to 500 (use decimal unless you want to manually convert the number to hexidecimal). (This key might have a different code at the end).

Open up the game, and watch all the achievements rain in.

Additional tip: you can edit the number of stars (in-game currency) here as well to buy all the cosmetics or all of the upgrades, or enough items to last you longer than this game will entertain you.
Simply edit "Star_h2089400753" to however many stars you want. (This key might have a different code at the end).