Pause the game and then press Left, Left, Right, Right, Left, Left, Right, Right, Down, Left, Right.
Mars Tracks
At the main menu press Right, Left, Right, Up, Down, Left, Right, Up, Up.
Martian
Pause and press Left, Left, Left, Right, Right, Right, Up, Up, Up, Down, Down, Down, Left, Left, Left, Right, Right, Right
Wide Angle