MadStone
High gravity:
-------------
At the main menu, press Down four times, Right, Left, Right, Left.
Low gravity:
------------
At the main menu, press Up two times, Left two times, Up two times,
Right two times.
Player skulls in Arcade mode:
-----------------------------
At the difficulty selection menu, press Up, Right, Down, Left, Up,
Right, Down, Left.
Savant mode:
------------
Select Single Player mode in Arcade mode. Press Down ten times at the difficulty
selection screen. The pointer will move underneath the Master difficulty, and
the game will start in Savant mode.