I decided to take a stab at contributing some material to Zak S's crowdsourced Gigacrawler RPG. Here it is...
Wyrmholes- In ancient times it is said that the Great Wyrms coiled themselves around the geological faultlines of the heavenly spheres, burrowed deep beneath the tectonics plates. When the Gigastructure filled the spaces between celestial bodies the wyrms were free to roam, their tunnels trailing for millions of miles in seemingly random directions. Wyrmholes are perfectly smooth, their tunnel walls perfectly frictionless- enterprising Crawlers can ride these tubes from region to region at maximum falling speed, although such a means of travel is not without its hazards. Upon encountering an unfamiliar wyrmhole, roll 2d6:
2. Dead End- Aeons ago a Great Wyrm perished here in the midst of the Gigastructure. Unless they have some means to brake themselves suddenly, Crawlers will take maximum possible falling damage when they reach the end.
3. Non-Euclidean Wyrmhole- the Great Wyrm which carved this tunnel blundered across an interdimensional faultline, causing the Crawlers to teleport to a random location in the Gigastructure (with a possibility of reappearing in solid matter).
4. Relativistic Wyrmhole- the track of the Great Wyrm transits the gravity well of a supermassive object, such as a neutron star or a black hole. Crawlers will suffer the effects of time dilation, arriving d100 years later than they had started
5. Quantum Wyrmhole. A tunnel which forks 1d4 times, each branch representing a different quantum state. At each juncture there is a 50% chance of taking the wrong path.
6. Unstable Wyrmhole- Due to the nature of the local Gigastructure matrix, the tunnel bored by the Great Wyrm is not entirely smooth. Unless the Crawlers take special precautions they will take 1d6 points of damage per round due to friction and minor abrasions.
7. Stable Wyrmhole- A perfectly traversable tunnel from start to finish, though be sure to check for wandering monsters and other Crawlers .
8. Unstable Wyrmhole (II)- The Great Wyrm's tunnel traverses a pocket of inherently unstable matrix in the Gigastructure (d6): 1. Mud, 2. Silt, 3. Water, 4. Air, 5. Steam, 6. Magma. Crawlers must find means to traverse the hazard or become stranded.
9. False Wyrmhole- This tunnel, despite its appearances, was not carved by a Great Wyrm but something else entirely of the DM's devising. Roleplay accordingly.
10. Möbius' Wyrmhole- Somehow the Great Wyrm who carved this tunnel bent back upon itself in an infinitely recursive track. Crawlers must find an ingenious way to break the cycle or ride this loop forever.
11. Wyrmhole to Nowhere- This tunnel empties out into the Void itself, the space between spaces in which the Gigastructure itself is situated.
12. Live End- Crawlers have stumbled upon a wyrmhole that is still in the process of being carved... by a live Great Wyrm!