Here's your stinky cavern

Suddenly there's a game on for Friday. I should be prepping the town the party will probably head for. Instead, I now have a procedural cave system. Ah, the sweet fruit of procrastination. (Why write this up? Because the players ran to the edge of my prep last session when they asked what was down a twisty tunnel into the underground.)

The physicist in me wants to look into graph theory to see if this branches enough to be interesting. Simulationist tendencies scream for ways to reconnect branches, add rivers, faults, old mines and so on. (Basically I'm in jealous awe of Veins.) My few programming neurons wonder if I could automate this easily. And my inner DM is seething that it needs more dakka traps.  In any case, this cave system is out of my head now. Finally, time to fill a town with messed up Halflings.

Exploring cave system near Gatherhold

Tunnel sneaks down in turns and inclines; branches and connects to caves, underground river and chasms.

Roll 1d10 & 1d4, every stretch of corridor is 1d3 x 50 yards:

1-2 slope down; 3 slope up; 1-3 left, 4 right	7 chamber, 1-2 other exits; encounter
4 level stretch; 1-2 arcs left, 3 right, 4 ahead	8 hard climb to 1d2 exits 20 ft up/down
5 split into two; 1-2 up, 3-4 down	9 ends in flowing stream to other area
6 steep incline; 1-3 down; 4 up; climb 15 (10 w/equipment) or fall 1d6 damage	10 1 dead end; 2-3 perception 15 finds tight squeeze; 4 hidden doorway

Every 3 rolls on the table above, roll for encounters. Each time you roll 7 or 8, pick a new creature from the list. Entries 7 start unfriendly, entries 8 start neutral. Skill checks are athletics / acrobatics to avoid hilarious flailing, falling, noise, random encounter checks, and ending up as nom for the local eldritch aberrations.

1 slippery (wet or pebbles) - Dex 10 or fall, 1d3 nonlethal; Dex 15 & 1d6 lethal on incline	5 fast flowing stream; athl 15 to cross safely; 10+ slip 1d3nonlethal, soaked <10 swept away to other room; 2d6dmg
2 low ceiling - medium sized creatures roll acrobatics 15 to progress. <11: stuck, same roll or 1d3 dmg to tear free	6 pool of water; 1-3 clear, 3: small animals 4-5 bones, violet fungus 6 clear, odd taste - bowel cramps con 13 - 1d4 dmg, poisoned 1 hour
3 narrow ledge alongside pit; acrob 13	7 as 1-6, Darkmantle/Dolgrim/Dolgaunt
4 chasm, 10xd10ft deep & 1d3x5 feet wide; jump or climb to cross.	8 as 1-6, Colony Spider/Nothic/Myconid/Xorn