IN KARMA...

On the startup menu, after the screen size, it says "PRESS JOY 3 TO CONTINUE".
I found out that Joy 3 is Action on the keyboard.
What key is "ACTION"?

I'm not sure if I'm using the default key bindings, as I have this game for quite some time and I may have remapped the keys, but Action is A, for me. In the folder where you installed the game there's a program called setup, just open it and check the keys there. You can also configure them to your liking.

Hope it helped!