Yes I am pretty sure it is GPL, it was in SuSE 8.
I just played the first level and it needs 8 controls to be fairly playable.
right, left, up, down, forward, backward, missile, laser.
Not including hold you have 7 on the iPod (including scroll left/right). My iRiver has 9. Cut out reverse or missiles and you have 7 controls.
Sorry about my bad spelling, I try to spell check as much as possible...