if you try to promote freedom and free code
That's the thing, the GPL isn't about free code, it's about free software. It's about the end user's freedom, not the developer's. That's what differentiates it from the BSD license.
4-way movement for Crazy Kong / Donkey Kong is more difficult as the Tankstick has 8-way movement
I was going to say the same thing. I bought it specifically for Ms. Pacman, Donkey Kong, and Frogger, and unfortunately it's unusable in all 3. A keyboard works much better.