The Megadungeon in the Mutant Future

James had a thought provoking post about megadungeons over at Grognardia this afternoon, and it made me want to share a little about my own post-apocalyptic megadungeon.  This first post will be a session recap of the first expedition into the megadungeon, and I plan subsequent posts detailing the party's later (and much more thorough) explorations as well as a "behind the screen" look at how I run a megadungeon (sneak preview: add 1 part map, 1 part critter encounter list, a dash of preparation in the form of quick notes on areas, and a whole lot of winging it and that is Grandma Nashes Old Fashioned Megadungeon recipe!).

In the first few sessions of my campaign I had thrown out a bunch of possible plot hooks to see what the players wanted to bite at.  One involved a group of cephalopoid traders showing up in Spanky Butt with a ton of strange artifacts and a story about exploring a building to the west in the swamp, causing a cave in, and releasing an outpouring of thick, hot mist.  As the swamp used to be covered night and day in a similar mist, allowing the dreaded vampire bats to fly around at all hours, the players were quite keen to get to the bottom of this and "turn off the mist" as they put it.

So I cobbled together a couple maps of two high rise buildings that I snagged on Google image search, sunk them into the earth, drew connecting passages between the two and called them an ancient military complex.  This worked quite well as the basis for my megadungeon, as both floorplans allowed for choice in exploration both within a level and between levels.  I drew several expansions off the sides of the buildings (being underground, I was not constrained by the footprint of the ground floor as an actual high rise building is).  Multiple stairwells and elevator shafts connected the levels, and it was out of one of the open elevator shafts that the mists were pouring.  I made a few quick notes about the general theme of each level, wrote down a few reminders to myself (effects of prolonged exposure to the "mist", which was really the noxious atmosphere of the Oozyxphgian homeworld pouring out of an open portal in the lowest level, visibility in the mist, where the active security cameras were and what sort of security robots were still working), and went to the next session ready to wing it.  I had sketchily keyed the top level and the rooms directly around each entrance to the second level.

Well, the best laid plans of mice and Mutant Lords, as they say.  The players were totally freaked out by the cameras tracking their movements and the oppressive mists and they ran through the first level in the direction that they could feel the mists coming from and came to the open elevator shaft.  They tossed some debris in and realized they were standing in front of a drop of at least several hundred feet (actually more like 500' to the bottom!).  I described the metallic clickety clack of the spider bots that were closing in on them and the heavier thud thud thud of the scorpion's armored legs following close behind.  And thats when the party surprised me, as they are wont to do.  Bozko the giant shapeshifting mutant plant altered his form to completely fill the elevator shaft and I told him that the mist was pressurized and began lifting him up toward the top of the shaft.  He changed his form slightly to allow the mist to stream through several holes in his body and told the rest of the group to climb on top of him.  He enlarged the holes enough to decrease the pressure to the point that he began descending the shaft.  They ignored all the side exits and went straight to the bottom, all the way down to the 7th level, ignoring everything that I had prepared.  Good thing I had made a few notes on the main themes of each level!

I knew that they had just emerged in a vast hangar, filled with the twisted wreckage of old military vehicles of all descriptions.  The mist was incredibly thick down there, as the atmospheric pressure of the Oozxyphgian homeworld is quite a bit greater than that of earth, so the fumes were being pushed through the portal by the crushing weight of an alien atmosphere.  As I described the fused remains of the tanks and unmanned drones  emerging from the choking fog that they were walking through, I also told them that they could hear something clattering down the sides of the elevator shaft above them.  They fought against the streaming mist and made their way to its origin, two peculiar poles of an unknown metallic composition, between which a shimmering gate opened into an alien landscape.  The air breathers in the party were making saves every minute of game time or taking damage, and were slowly dying.  As they tried to figure out how to shut off the gate, the spiderbots and scorpion made their appearance and I thought I might have a TPK on my hands.  Well, it wasn't my fault they had chosen to descend all the way to the near airless depths when they could have fought the robots on their own terms 500' above!  Nowhere to run to, baby, nowhere to hide.

Cue party surprising Mutant Lord, part two.  Millard Fillmore, the intrepid swamp trapper, mutant human and NOT the 13th president of the United States despite many vociferous claims to the contrary, has a light-controlling mutation which he used to displace the laser targeting dots the spiderbots were shining on the party back onto one of the spiderbots.  The scorpion launched some missiles, and most of the spiderbots were vaporized.  Unfortunately, some of the party was caught in the radius of the explosion and also suffered some near fatal damage.  Meanwhile, the two technologically inclined party members were hard at work messing with the gate.  They figured out that the seemingly seamless pillars actually were composed of 8 rotating sections, each of which clicked into 8 different positions as they were rotated (that was complete improv on my part, I had not got as far as figuring out how the portal worked or how to turn it off!).  They began twisting the sections and observing the results as the rest of the party tried to hold off the robots.  Someone had the bright idea of hiding on the far side of the gate (which was one sided - that is the mist only poured out of one surface of it and from the far side it simply appeared as a rippling obstruction of space) while Millard projected the image of the party in front of the gate so that the fire of the scorpion would go through the gate and explode harmlessly in an alien world.  This worked on the scorpion, but the remaining spiderbots had much too sophisticated sensory equipment to be fooled for long.

In the meantime, however, I had been having the two tech-heads make tech rolls to see how much progress they were making on the gate.  I had decided on the spot to start out with a relatively difficult benchmark and every roll above that would cause the gate to expand, while rolls below it would cause the gate to contract.  Each roll that caused a contraction would raise the benchmark, making it progressively easier to shut it down - I reasoned that since they were observing the effect each manipulation of the pillar had on the gate, it would be easy to tell what was working and what wasn't.  As the spiderbots were making their way around the gate and picking up the actual position of the party, the players managed to shrink the gate considerably with several very low rolls.  The spiderbots targeted the party using their vibration sensors, and signalled their position to the scorpion.  Just as the scorpion began to come around the portal to unload on the party, the tech guys rolled a near critical failure.  I think they got a 98 on a d100, or something like that; in any case, the portal expanded dramatically and swallowed the scorpion up in its expansion.  Their next roll was ridiculously successful, a 3 on d100 minus their combined bonuses put it at something like -20.  I ruled that they had closed the portal, trapping the scorpion on the other side.  It just seemed too dramatic and serendipitous an ending to pass up.  The remaining spiderbots quickly high tailed it, lacking any firepower of their own.

Most of the party was near death and everyone except Dataan the robot (who had actually not revealed to the party yet that he was a robot, so he was pretending to be suffering along with the rest of them) and Bozko the plant were about to succumb to the poisonous gases that still filled the chamber.  They went back to the elevator shaft and quickly realized that without the atmospheric pressure pushing the mist, there was nothing to propel them up the shaft!  They were 700' below ground and had to start up a stairwell to get out the hard way...

And that is how the party truly began the exploration of my megadungeon, from the lowest level up!