Robotron Level select: Press Down, Up, C-Left, Down, C-Left, C-Right, Down, C-Right at the setup screen. Fifty lives: Press Up(2), Down(2), Left, Right, Left, Right, C-Left, C-Right, C-Left, C-Right at the setup screen. Monochrome mode: Press Up, Down, Right, C-Left, Down, Up, Left, C-Right, Up, Down at the setup screen. CPU control: Quickly press [Left, Right, Up, Down, Left-C, Right-C, Left-C, Right-C] three times at the setup screen.