MAP15: Dark Entries (Doom 64)

Dark Entries begins inside of a small nook, with faces on the walls staring at the player. One of these lights up the next area, while the other blocks one of the fireball launchers. Upon exiting this nook, the player is greeted with a horde of Nightmare Imps and Lost Souls, and to make matters worse, homing fireballs pour out of launchers, which happens each time the player re-enters this room.

After leaving through a side door, the player finds themself in a room with a a few pillars and an open ceiling, and concealed Arachnotrons take potshots at the player. A switch activates a puzzle in which the player predicts where a Soulsphere will end up, after which a flock of Lost Souls appear, and so does the blue key.

Back in the main chamber, more Lost Souls appear, as well as more fireballs. Using the blue key to open a barred area, the player finds what looks to be a castle, surrounded by Arachnotrons, Barons, and Hell Knights, both loose and caged. The castle itself is filled with Lost Souls, and the player finds a red key for their troubles.

After going back to the main chamber, the player is attacked by not just Lost Souls and fireballs, but Arachnotrons, too. Using the red key opens up the exit, guarded by a number of Barons.