Valis 3

Debug mode:
Press II, II, Left, Right, Down, Up, Run at the title screen. Press II to select between a music test, message test, and animation test, and I to play the current choice. Note: For the Japanese version of the game, press I, I, Up, Down, Right, Left, Run at the title screen.

SD review (Japanese version):
Press [I four times, Up, Up, Down, Down, Right, Right, Left, Left] two times during the opening animation. Then, press Run. Alternatively, press Up + Run when Grames appears with the sword.