Image by Peter Mullen
Castle Xyntillan - Megadungeon
A castle left to time and the elements. The promise of treasure occasionally draws the foolhardy and less than scrupulous adventurers to its grounds.
$20.00
/ Session
Details
2 players following this game
Weekly / Tuesday - 11:00 PM UTC
Session Duration / 3–3.5 hours
3 / 6 Seats Filled
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Meet your party members
3/6
About the adventure
Just beyond a small forest town, a road forks at a mountain's base. Despite its unassuming appearance, even the briefest glance toward the high path is enough to put fear in most and steer them toward the other. A two-day climb on the path through pine shadow eventually leads to a crystal-clear lake. Above it, the crumbling parapets and fantastic towers of Castle Xyntillan: several centuries of architectural folly, wings raised by different hands in different ages, with little regard for past additions. The final recipient of the grounds gave it up as too costly, leaving it to time and the elements. The occasional fortune seeker still takes the high road, never minding the ghost stories. This is a great module for new and experienced players alike, offering tense exploration, strange discoveries, and plenty of space for player ingenuity. Xyntillan is enormous and runs as an open campaign, so expeditions go in, come back out with what they can carry, and go in again. Depending on the speed of play, this could be 10 to 30 sessions or more. I've also been wrong before on number of sessions many times and try not to rush players who want to spend time on any given location. I use the Advanced Fantasy version of Old-School Essentials in addition to some of the rules, classes, and races from the Carcass Crawlers 1-6. Your characters from my other OSE adventures that fit this adventure may be used.
Game style
Dungeon Crawl
Rules as Written (RaW)
Game themes
Meet the Game Master
5.0
(9)
2 years on StartPlaying
21 games hosted
Highly rated for: Creativity, Sets the Mood, Beginner Friendly
About me
Hi, I'm Ryan and I have been playing TTRPGs since the 90s. I began DMing in 2019 with 5e and eventually switched into OSR games, primarily Old-School Essentials. I ran a drop in Shadowdark campaign at my local library for kids after school up until I had my first child. In 2026, I ran OSE as an official Grave Master for Exalted Funeral. I also play quite a bit, both in person and on StartPlaying weekly.
View Profile →Character creation
Creating your character
I have pre-generated characters available, but also welcome rolling characters ahead of time in Discord and will help you get those into the VTT ahead of time.
What to expect
Preparing for the session
Foundry VTT and Discord for voice communication.
What Ryan brings to the table
I use OSE's exploration and combat procedures, streamlining it with a Foundry module to make things easy. I also use music and environmental sounds in Foundry to add to the immersion of the session. Players will be able to access the Player's Tome in Foundry as well as the applicable rules from the available Carcass Crawler issues. I spend a lot of time prepping Foundry to deliver smooth gameplay and less time fighting with the VTT.
Homebrew rules
These are the rules I incorporate from Necrotic Gnome's Option Rules Checklist (https://necroticgnome.com/products/old-school-essentials-optional-rules-checklist): Ascending armor class, full hp at level 1, detailed encumbrance, separate race and class, arcane spell casters and staves, human racial abilities, attacking with two weapons, parrying, +2 to attack rolls made behind target, and more. My own homebrew rules: I like to use some of the rules from Dolmenwood, Gavin Norman's other game as well as others. Some of those are here: When reduced to 0hp, 2-in-6 chance of death, allowing teammates a chance to aid. Fumbles and crits in combat.
Equipment needed to play
Internet
Computer
Microphone
Platforms used
Safety
How Ryan creates a safe table
Breaks, deck of player safety, and open door will be used as well.
Content warnings
Safety tools used