I decided they were the only survivors of a frontier village just off map to the south that was hit by massive earthquake that created a chasm that stretched across their route to the south where civilization was. So they headed north.
They made it to the first castle before their food ran out, after finding horses and capturing them.
On the ride in, they had a moment of pause when they spotted orcs on the battlements. They collectively shuddered when they saw a red dragon perched on one of the towers. A big dragon. When the second dragon fly into view, even bigger than the first, they really worried . By now, they were escorted to the castle, so they had no way out.
So it turns out this castle is run by a 10th level magic user named Zatherop, his four apprentices, 110 orcs, and a staff of 100 humans. Chaotic of course. He either wants a magic item, 3000 gp, or to send them on a Geas (per normal OD&D/DD stronghold rules). As starting 1st levels, they had no choice but to be Geased..
At this point, I pulled out Dyson's Delves to look for a map. I picked the Halls of Surreth, a nicely sized level that would take a few attempts to explore that also had room for expansion.
The next morning they head out, with provisions restocked, saddles for the horses, and three mules, in case they need to haul out treasure. It takes a day to find the path and another day to find the cleft in the mountain. So they enter the dungeon.
After taking out a large spider and a few large centipedes, they explored a room that seemed interesting. They found a wall that was an illusion that hid a small nook in the room. They found three bags of silver (40 pounds each), three bags of gold, and some jewelry, one tiara of which was surely pricey.
The next room held a red dragon hatchling. In a daring move, they tried to subdue the young drake. In the first round, the Swashbuckler got caught in fire breath, dying horribly. But they managed to subdue it in another round with no casualties.
They felt this baby dragon would make a good addition to Zatherop's other dragons, so the party left the dungeon, getting out through some more centipedes. The dwarf had to cast runes of Cure Light Wounds to cure the paralysis on the warlock. They made it back to the castle, and, indeed, Zatherop was mightily pleased by his new minion. He gave them another fabulous feast, and let them stay for another week, then sent them off with fresh provisions, plus the saddles and mules he had lent them.
Oh, and they all went up to 2nd level. I think they're going back to the Halls of Surreth to see what else is there.
The wilderness and the dungeon room contents tables all worked well. I was really pleased with how the randomness worked out with the dragons and the hatchling. They now have a powerful wizard that thinks well of them. Next time I need a little break, I can pull these folks out and run a few more days of exploration.
Here is a list of the resources I used for this experiment: