This story has nothing in common with the Main Story doctor's appearences.
Though this game mode is very short (it can be beaten in less than 20 minutes), it's very hard. Its default difficulty is Medium, but there are more monsters than in any other part of the main story.
There are no tape recorders to save, no way to regain health (pills, syringes... ), and the only weapon available is the Taurus Revolver, which is powerful but also slow to reload and quick to unload, so one must be careful and avoid enemies as much as possible, in order to save ammo and health.
Completing this scenario will grant the player the Doctor's Gasmask for the main scenario, which can be picked up in the Secret Rooms.