I cant install my product key not sure what to do
Can you be a little more specific? Give us more details? Where did you buy the game, how did you download it, etc?
You can also try hitting me up on the Discord - I'm K75 there. :)
https://discord.gg/XWZhWa
If you have purchased the game through the Knuckle Cracker website and received an e-mail with the product key, you should also have received a link to the download of the game. You can then launch the game and type your product key in there. If you missed it, you can download the game you purchased at one of these places, depending on the game:
Particle Fleet: https://knucklecracker.com/particlefleet/redownload.php
Creeper World 3: https://knucklecracker.com/creeperworld3/redownload.php
Creeper World 2: https://knucklecracker.com/creeperworld2/redownload.php
Creeper World 1: https://knucklecracker.com/creeperworld/redownload.php
If this does not solve your issue, you will have to be more specific, as K75 said, we're not sure what exactly is the problem you've run into.