How To Invent a Role-Playing Adventure, Part 1

I’ve been working on a D&D adventure, War in the Deep. It’s an underwater adventure in which the players are transported to an undersea kingdom, where they have to rescue a princess consumed with bloodlust.

(Which, incidentally, you can buy at DriveThruRPG for $5!)

Anyway, here’s how I designed it:

I started with the reason for the adventure. This was originally part of a larger campaign, where the players are seeking seven different magical stones, and the king of this undersea kingdom has one of them. So, they were going to travel there to meet him. The question was, what would prevent the players from just requesting and taking the stone back from the merfolk?

I didn’t have a good answer for that, so I began flipping through the Monster Manual to get ideas for the creatures that might be in that area. That’s when I stumbled on the sahuagin.

The sahuagin are nasty brutes who mostly raid coastal towns. They’re basically underwater goblins: they sneak up out of nowhere, attack anyone they find, and steal supplies.

Sound like fun antagonists. So what if they’re the real antagonists? What if they’re attacking the undersea kingdom?

Okay, so how to get the players involved in a war between the merfolk and the sahuagin? Well, the players are traveling to see the king. What if his daughter is in danger? An easy reason would be kidnapping; let’s flip that around. What if she went off in search of danger, lusting after sahuagin blood?

And there was my plot.

So then it was a matter of designing the conflicts. I wanted to expand the time spent traveling to the merfolk’s central city, so I added an early encounter with a sahuagin raiding party. I then added an enclave of aquatic elves who would help the players get through that area if the sahuagin proved too powerful. I also conjured up a High Council of the aquatic elves, who could answer the players’ early questions about this area of the world, and the conflict between the merfolk and sahuagin.

After encountering the merfolk king, the players then had to find the princess. I figured the king would know at least roughly where the princess was, so I made that easy; the players just traveled north to a border town. On the way, they traveled above abandoned merfolk villages (as the merfolk prepared for war, they abandoned their easily-attacked villages).

Up to now, the players had been fighting sahuagin raiding parties, so I wanted to get across the feel of a large war. So I designed the next battle was a real battle, with dozens of sahuagin and several siege weapons assaulting this northern border town. The princess is in among the fray, giving it something of a Battle of Helm’s Deep feel.

Now what? How to finish this up with a satisfying ending? I’ll let you think about how you’d do it, and I’ll answer in part 2.