MAP21: Failed Experiments and Trashed Aircraft (BTSX-E1)

MAP21: Failed Experiments and Trashed Aircraft is the twenty-first level of the first episode of Back to Saturn X. It was designed by Nick Laurent (Hobomaster) and Richard Frei (Tarnsman), and uses the music track "Heliotrope" by James Paddock.

Walkthrough

 * Letters in italics refer to marked spots on the map. Sector numbers in boldface are secrets which count towards the end-of-level tally.

Secrets

 * 1) Sector 194: In the room with many barrels and armor on a high platform, press the switch to lower the platform, then press the switch that raises the platform while quickly running back towards the platform. Ride the platform to the top, then shoot the switch on the far wall. Run through the door up the stairs, then follow the stairs up until you find a doorway marked on either side with blue lights. Enter here and an elevator will lower. Ride the elevator down, then enter the door. Enter the hallway and open the next door. Inside is a plasma gun, megaarmor, and medikits. Once the secret is triggered, an arch-vile will spawn behind you.
 * 2) Sector 456: Go down the slime corridor west of the blue key room. At the end, go up the lift. Turn around, and shoot the switch on the opposite platform. This raises a walkway to the platform, where a chaingunner can be found.
 * 3) Sector 541: Just inside the blue key door is a round grate with a candle in front of it. Punch the grate to break it open, then enter the vent shaft. The vent tunnel forks two ways, with the left path having a dead end with two armor bonuses and 4 shotgun shells. The right path has another grate at the end. Punch it open to reach the soulsphere inside. Note that the grates may also be shot open, but this wastes ammo. The chainsaw works as well.
 * 4) Sector 549: In the south-east of the map, find a way into the nukage itself, rather than the bridge. The south-west of this room holds a dark tunnel. A backpack and radiation suit are inside.

Speedrunning
The records for this map at the Doomed Speed Demos Archive are: Last updated on 16 March, 2013.

Things
This level contains the following number of things on each skill level:

Inspiration and development

 * In versions of Back to Saturn X up to 0.99i8, this map held the MAP20 slot. In versions starting from 0.99i8, the addition of a new MAP19 moved some maps forward by one slot.
 * The name for the map was chosen by Richard Frei. The name was inspired by the fact that the original version by Nick Laurent went over vanilla limits in many places, thus several of Laurent's "failed experiments" had to be "trashed" to make it vanilla compatible.