Approaching City 6
I've been thinking about this old-school Gamma World megadungeon on a huge scale. Some sections of the dungeon are loosely detailed using rough guidelines and random tables int he style of Zak Smith's Vornheim City Guide. Others are fully mapped and statted.
City 6 is an abandoned arcology that completely spans a ravine with a river flowing down the middle of it. The other end of the arcology forms a massive hydroelectric dam, but this information is probably unknown to the PCs.
The front wall of the complex is composed primarily of hab pods, each of which is a neighborhood of dwellings with room for 200-1500 inhabitants. Originally, the habs were modular, self-contained units, each with its own AI, and a layout designated by the owner. Most are now horribly broken down. The lower units have been broken into and looted, and may be inhabited by native life forms. Some of the higher units are more or less untouched.
The layout of each pod is determined by a geomorph system. The current state and contents are inspired through a set or random tables.
The habs are an obvious spot for a first adventure, although more intrepid groups might enter through the effluvium, a great pipe that leads directly into the dangerously dilapidated processing plant deep in the Microdungon, and from there to the Garden district. If a party can reach the roof (no mean feat), they also might find their way to the central dome.