I'm using macOS Catalina 10.15.5 and it wont let me open the game. Normally I can unlock it in to allow this  by confirming the developed is trusted but in this case the pop up just says:

The application “WalkthePlank” can’t be opened.

If you click the question mark it brings up an empty assist page so no ideas there. Is there a way around this?

Same. I am also using Catalina.

Hi !

I'm not on Catalina but on BigSur and my App just kept telling me I couldn't open the game unless I contacted an admin (as of it wasn't me already) so that worked for me :

open terminal. 
enter sudo chmod -R 777
then drag and drop the application you are trying to open.
click enter

And you'll surely have to make it open through the settings but it opens at last !