Incandescent Grottoes: Why This Module Is Perfect for Your Campaign
This is an amazing module. Play it with B/X, Old School Essentials, Basic Fantasy, or even 5e if your players understand they might actually die. Let’s get into it.
The Maps
Multi-level dungeon with loops everywhere. You know I love loops. Players can enter from one side and find so many different paths through. There are stairs down, river passages, even teleportation.
No singular way through. Multiple routes, fast travel options for clever players, and plenty of ways to get lost. That’s what makes dungeons fun.
And the maps are gorgeous. Everything in Old School Essentials is probably the best design I’ve ever seen for running at the table.
Connect It to Hole in the Oak
Both dungeons have rivers running through them. String them together for a massive interconnected dungeon. If you’ve run Hole in the Oak, this is the natural expansion.
Facing Pages Design
This is the design philosophy that makes OSE modules a dream to run. Everything you need for a set of rooms is on two facing pages. The map section on one side, room descriptions on the other. No flipping back to reference a distant map. No hunting through the book.
You just open to the right page and run the dungeon.
Factions and Relationships
The module gives you factions and the relationships between them. You know exactly how groups interact, how players might play them against each other. Smart parties have tools beyond combat.
Room Descriptions That Work
Look at this format:
“Crystal Grotto. Metallic gray crystals hanging from the ceiling. Sandy white floor like a beach. Glowing moss enveloping the walls like a blanket.”
Bold headers for instant scanning. Bracketed expansions for when players investigate. You glance at it once and start describing. When players look closer, you read the details.
For monsters:
“Sniveling canid humanoids” (the original dog-faced kobolds, not the dragon kind)
And crucially: “Hates gnomes. Attack on sight.”
That’s all you need. You know immediately how they’ll react. If there’s a gnome in the party, it’s over.
Risk and Reward Done Right
There’s a room full of flesh-dissolving jelly. Objects visible inside. Players can see treasure. Now they have a problem to solve. How do I get it out? What’s it worth to me?
That’s what puzzles should be. Not riddles with one answer. Situations with costs and choices.
The Sigil of Jellification: a purple slime ring on the floor with small jelly piles nearby. If players examine them, they look like squashed gelatinous rats. Step inside the ring? Save versus death or get turned to jelly.
Brutal. But the clues are there. Players who pay attention survive. Players who rush in become another jelly pile.
The Doppelganger Story
There’s a doppelganger disguised as a friendly old woman. In my game, she befriended a player, waited for the right moment, killed them, then dragged the body to the skull statue (touch it and you disintegrate), destroyed the evidence, and became that player.
The player had a choice: roll a new character or become the doppelganger and spend the rest of the session looking for opportunities to kill other party members.
They chose doppelganger.
That’s what these modules do. They create situations, throw players in, and something unexpected happens every time. I couldn’t write that into a module. It emerged from play.
The Trites
A ragtag bandit gang in disarray after their leader was murdered by a rebel faction that’s since fled. Prime material for players to manipulate, ally with, or exploit.
Every faction is a situation waiting for players to interact with it.
Janitor Zombies
There’s a crypt area with zombies that maintain the graves. They’ll follow instructions and leave you alone. Unless you mess with the tombs. Then they attack.
It’s not just “zombies attack.” It’s zombies with a purpose and a boundary.
Bottom Line
Incandescent Grottoes is brilliant. The design makes it effortless to run. The factions give players options beyond combat. The rooms are full of risk-reward choices.
Connect it to Hole in the Oak for a massive dungeon complex. Run it standalone for a complete adventure.