Hide player character
Rooms have a tickbox called "Hide player character" which can be used for title/menu/credits screens, etc.
If this option is ticked, the Character.on property holds 0. This undocumented variable is normally 1, but you can also set it to 0 to make any character invisible.
But note that Character.Walk and the like don't work with characters turned off this way.
Another way to do this is directly modifying the Character.room property. This won't prompt a room change, it'll just make the player character disappear.
This option is useful for first-person views, or the cut-scenes when the main character doesn't take a role (for example, while showing some other characters' talking).