I've installed Crpytark through the Galaxy client, like all my other GoG purchases. Won't start at all. Tried uninstalling/reinstalling, verifying the installation through the client - nothing. All other games, even much more demanding ones, work flawlessly.

This might be the solution for some people:

To run Cryptark, you'll need XNA framework 4.0. My Win10 install didn't have any XNA on it by default. After installing it, Cryptark fired up no problem.

Strange that the Galaxy installer didn't check for these kinds of dependencies.

Thank you! I had the same issue and installing the XNA framework solved it too.