I've been working on this supplement for a while, using maps that I drew for Star Wars RPG scenarios and retooling them for use in Spelljammer adventures. The post below is a preview for the Oasis.
-Nate
Desert Oasis
This large structure, built from dried clay bricks, is relatively simple in nature but impressive in its achievements. It consists of a dozen landing bays (see below), which can be left with floors of packed earth or flooded for landings on water, depending on the needs of incoming vessels. Double doors on two sides provide access for people who are coming and going, and in the middle there is a large open area that serves as a campground and a marketplace. Vendors come from all around to sell their wares; some set up semi-permanent stands, while others just pitch tents or roll out carpets. In the middle of all that are two other buildings, a cantina and a warehouse. All around the outside of the structure are fruit trees and fields of crops, which are irrigated by the overflow of water from the Oasis. In that way, it serves as a small hub for agriculture in addition to being a starport.
The cantina is pretty typical of its type around various Wildspace systems. Inside the front doors is a broad, open room (1) filled with tables and chairs. There is a bar lined with stools against the back wall. Behind the wall a door leads back to the kitchen (2); off of that is the storage room (3). There are two private rooms (4) in the corners, available at extra cost. Similarly, the warehouse consists of a loading dock (1) which, along with big double doors, leads into a broad, tall room filled with storage shelves (2).
Broad double doors (1) provide access to the landing bays. Each one has a broad central pit that is 140 feet in diameter (2) in which ships can land. As mentioned above, the sandy floor can be left dry, or the pit can be partially flooded with water to allow water landings. Three doors lead from each bay into the other rooms. One is a bunkroom (3), with beds along the outside walls, a table and chairs in the middle, and shelves for personal belongings. Another is the kitchen (4), with more tables and chairs, a broad table for preparing food, a hearth on the outside wall, and cupboards that hold pots and pans and other implements. Finally there is a room (5) with a well, two privies, and tubs for taking baths. This is pretty luxurious by frontier spaceport standards.
Location
This frontier port is a natural fit in any location that has a hot, dry climate. On Toril, that means the Calim Desert, the Haunted Lands or Anauroch. Oerth has the Bright Desert, and Krynn has the Plains of Dust. When it comes to more obscure worlds, the planet Ashen in Pyrespace could be a good fit.
Inhabitants
Detailed below are some of the major inhabitants of the Oasis.
The proprietor of the Oasis is Ennu Talik (use the Tribal Shaman variant of the Druid stats from page 346 of the DMG). During her explorations she found a decanter of endless water and realized the potential it had for creating an oasis such as this. While some of her fellows balked at the idea of settling down permanently, others recognized the comforts that could come from such stability.
Ennu is assisted by a dozen Tribal Warriors (DMG page 350) who keep the peace and assist visitors as needed. They dwell at the Oasis permanently, and are related to a tribe that lives in the area. When tribe members visitors arrive to trade for goods, they camp out in the landing bay occupied by this group.
Nilo is a retired githyanki buccaneer (BAM page 27) who runs the cantina and warehouse. He once sailed throughout Wildspace on a spelljamming ship, but was smitten by Ennu. Using his spoils from a recent adventure, he offered to build the cantina and warehouse in order to create more business. What he did not expect was to fall in love and give up his peregrinations forever.
Kassandra is a dryad (MM page 121) who dwells in the orchard that surrounds the Oasis. Her spirit was bound to one of the trees here by a powerful fey who thought it was a punishment. Instead, she has come to enjoy dwelling in this place, caring for the plants and animals and meeting the many travelers who pass through it.
Zurn is a plasmoid who, through easy living and casual theft, has grown into a boss (BAM page 42). See below for more about the shenanigans that he can cause.
Doing Business
The Oasis serves mainly as a hub for other people's trade. It has food enough for itself, of course, but not much too offer for sale. What it does have is plenty of water, and will fill casks and barrels as part of the docking process. Ennu and her people charge 10 gp per vessel that lands, and 5 sp per day for lodging at the inn. Those who camp out in the central marketplace are charged 1S sp per day.
Plot Hooks
Presented here are just a few of the intriguing developments that could take place in this port of call.
The PCs could be tasked with delivering a cargo of animals—chickens, goats, sheep or even cows—to the Oasis. That, in itself, is enough of a challenge. There could be locals who are opposed to this delivery, however, and that pushes the PCs to deal with them while also protecting the animals in question.
There is a plasmoid boss who lives in the Oasis (see above). In fact, he uses the pipes that connect the landing pits as his own private means of travel, moving from bay to bay to see what he can and take what he wants. The PCs might be one of his victims, or be recruited by another victim to help find the culprit.
This comes to a head when the plasmoid thief finds the decanter of endless water and steals it, then begins to demand money in exchange for keeping the Oasis running.
In times of trouble, the Oasis can serve as a refuge for locals, with its solid walls serving as a fortification.
That becomes important when a tribe of gnolls that lives in the area begins sending representatives to visit. They say they are just interested in peaceful trade, but some worry that they are scouting out the structure and looking for some kind of weakness that they can exploit.
Periodically, some of the tribe members venture out into the wilderness to hunt local game, both as a food source, for entertainment, and as a means of proving one's mettle.
When a sandstorm hits, it drives all of the local inside to take shelter. Some are found to be missing, however, and volunteers are sought to venture into the storm to rescue them.
As part of an origin story, the PCs could be inhabitants of the Oasis who prove their mettle in some kind of adventure here and then are invited to join a spelljammer crew.
For example, they might be recruited by Ennu and her people to help when the crew of a visiting spelljammer vessel turn unruly and start looking for a fight.
In the center of the Oasis, beneath the ground, there is a cistern buried. It is accessible via a trapdoor in the ground between the cantina and the warehouse, with walls built from mud brick in a similar manner to the walls of the compound. From it, four pipes lead out to each of the landing bays. At the mouth of each cluster it branches into three, leading to the wells along with valves that can be opened to flood the pits, to prepare for a vessel that needs to land on water. Finally, on the outside of each landing bay is another valve that can be opened to drain the pit as well as to provide irrigation for trees and crops growing outside.
The cistern itself is a circular chamber accessible via trapdoor and ladder on two sides, with ladders leading downward. On the other two sides of the chamber are pipes by which one can send water out to the landing bays and into the land beyond.
