There are four endings in the game

Unlockable How to unlock
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Ending A - Save Lombard, then leave the room when confronted by the murderer.
Ending B - Save Lombard, then throw the marble at the murdered when confronted.
Ending C - Do not save Lombard, then leave the room when confronted by the murderer.
Ending D - Do not save Lombard, then throw the marble at the murdered when confronted.