Marlone's birthday:
Set the Saturn's system date to November 5 and play the game.

Christmas greeting:
Set the Saturn's system date to December 25 and play the game to get a Christmas greeting from Marlone.

Long time comment:
Set the Saturn's system date three months ahead of the last day you played the game. Marlone will mention that you have not played in awhile.

Late night comment:
Set the Saturn's system time to Midnight or later. Marlone will ask if you are sleepy.

Bonus option:
Successfully complete the game. When the game is started again, a "Bonus" option will be unlocked. Select it to access "Art Gallery" (view artwork), "Music Theater" (sound test), "Central Theater" (view endings), and "Playpen" (play mini-game) options.