Type "levelx " (or "oh dear" if you have v1.2 or greater) in the
 main menu, do not forget the space. If you did  everything right
 a conformation will be displayed. Now you have:

 In the main menu you can select the mission areas by pressing [Alt]
 and a number key from [1] to [6].

 In the game you have:

 [Alt]+[1] - Ammo complete
 [Alt]+[2] - Weapon upgrade
 [Alt]+[3] - Energy boost
 [Alt]+[4] - Invincibility
 [Alt]+[5] - lol
 [Alt]+[6] - Mission complete, sometimes you have to do this twice
 [Alt]+[7] - Disable enemies
 [Alt]+[8] - Change to helicopter
 [Alt]+[9] - Change to tank (be carefull if you where a heli before!)
 [Alt]+[0] - rofl