MAP09: Nessus (PlayStation Final Doom)

MAP09: Nessus is the ninth map of PlayStation Final Doom, and the ninth map of the Master Levels episode. It is based on the PC version of MAP07: Nessus from the Master Levels for Doom II, with modifications to accommodate the PlayStation's framerate and memory limitations and add enhancements such as colored lighting. It uses the music track "Tendrils of Hate".

The author of the original level was John Anderson (Dr. Sleep). Changes for the PlayStation port were authored by Tim Heydelaar.

Essentials
Go through the door in front of you, then through the west door in the next room. Take the lift down and go west until you reach another door. Go through it and head up the staircase. At the top, approach the gargoyle switch on the west wall and the floor will lower to reveal a revenant, or two on Ultra Violence skill level (UV). Kill them and press the switch they were guarding.

Go north down the staircase and open the door at the bottom. Head east through a tunnel and keep going until you reach another door. Open it and climb the staircase - when you reach the top the east wall will open for a few seconds. Kill the revenant behind the door (on UV) and press the switch behind it to finish the level.

Other points of interest
The central building contains several weapons:
 * A chaingun is placed between the south doors.
 * A super shotgun is placed in the middle of the building between two brown walls.
 * A chainsaw is placed in the south-west cage, between two boxes of rockets.
 * A rocket launcher is placed at the south-west window.
 * A plasma gun is placed at the north-east window.

The room due east of the starting area contains a soulsphere (on HMP or lower), along with megaarmor and a computer area map (on HMP or UV). Approaching these items releases a revenant behind you on UV, or a Hell knight on lower skill levels.

The northern tunnel contains four teleport pads. From west to east, stepping on the pads will send you to the eastern-most room, the north-east window of the central building, the western-most room, and the south-west window of the central building.

Secrets

 * 1) Inaccessible: The north wall of the central building (between two metal supports) is false - walking through it will reveal a revenant guarding a ledge on the other side of a hole. Run over the hole and open the east wall that has a cross-shaped texture to find a BFG9000 behind it. The doorway counts as a secret, but the sector is too thin for the player to be recognised as entering it. (sector 57)

Bugs
Because the level's only secret is inaccessible, the end-of-level statistics always show 0% secrets. The inaccessible secret is also present in the PC version of the level.

Room design

 * All switches use a gargoyle face on metal wall texture (SW1GARG)
 * Several sectors used to provide varying light levels in the room north of the start point are removed. The room has a single light level throughout.
 * The staircases in the middle of the central building have fewer steps, along with the stairs by the east and west doors from this building.
 * The grate textures used in the central building are replaced with metal fences.

Monster placement

 * Demons and spectres are replaced with imps.
 * Hell knights and barons of Hell are replaced with revenants.
 * The zombieman behind the left-hand door in front of you as you leave the starting room is replaced with a shotgun guy. All other zombiemen are removed without replacement.
 * The cacodemon guarding the elevator north-west of the starting room on UV is replaced with a chaingunner.
 * The cacodemon in the northern tunnel (with the teleporter pads) is replaced with a mancubus on UV, and a chaingunner on Hurt Me Plenty (HMP).
 * A mancubus is added to the eastern outdoor area on HMP/UV.
 * The arch-vile guarding the room due east of the starting area on UV is replaced with a revenant.

Player spawns
This level contains five spawn points:
 * 1) facing north-west. (thing 4)
 * 2) facing south-west. (thing 5)
 * 3) facing south-east. (thing 6)
 * 4) facing north-east. (thing 7)
 * 5) facing north. (thing 8)

Things
This level contains the following numbers of things per skill level:

Technical information
In the PC version, the room immediately outside the start room has a pattern made from different brightness levels. This is absent on the PSX - the room is simply dark, a theme continued throughout the level, likely to reduce the level's footprint in memory without significantly altering its layout.

This is the only level of PSX Final Doom featuring mancubuses. This is likely due to VRAM considerations, given the large and complex nature of Final Doom maps.