The Ruins of Castle Greyhawk comes to D&D Beyond in November 2026: four adventures for levels 5 to 10 from Baldman Games, built on the 2024 rules, "featuring the iconic three towers and the dungeons beneath them" [1]. It is the fifth published go at a dungeon Gary Gygax started under his own house rules in 1972, and the owlbear's first home.
Arthur has the old modules' history at his fingertips. Rohan wants to know why anyone needs a fifth version. Both have a point, so here is the release, the history, and the maths for surviving a dungeon that has been eating characters for fifty years.
The Ruins of Castle Greyhawk: release date and what is in it
D&D Beyond's Q4 2026 partnered content schedule lists it for November 2026, publisher Baldman Games, edition 5.5e (the 2024 rules) [1]. The full pitch: "Delve into the ruins of Castle Greyhawk! Four adventures for levels 5-10 are included in this bundle, featuring the iconic three towers and the dungeons beneath them" [1]. No exact day yet; the schedule names the month.
| Month | Title | Publisher | Levels | Adventures |
|---|---|---|---|---|
| October 2026 | Heralds of the Old One | Baldman Games | 5-10 | 3 |
| November 2026 | The Ruins of Castle Greyhawk | Baldman Games | 5-10 | 4 |
| December 2026 | Beasts of Johrase | West Coast Adventurer's Guild | 1-4 | 4 |
It is approved for the Legends of Greyhawk organized play campaign, or as one-shots at home [2]. If you play organized, you need a level 5 character first. That takes 10 adventures from level 1; our Heralds of the Old One guide has the full counting table and the character rules.
One number worth knowing: in Legends of Greyhawk, every level from 5 to 10 costs four adventures. Castle Greyhawk has four. Play the whole bundle and you gain exactly one level [7].
Where D&D began: Gygax's home dungeon
Castle Greyhawk was never a product first. Gygax built it in 1972-73 as the dungeon for his own players, his children and friends, while he and Dave Arneson developed the game. Levels were written about one a week as play went on, until the castle ran thirteen levels deep [3]. Rob Kuntz started his own dungeon, El Raja Key, the same year, so Gygax could play his own characters in someone else's game, and parts of it were folded into an expanded Castle Greyhawk before Dungeons & Dragons was published [3].
Wizards of the Coast's own history puts two of D&D's most famous monsters there: the owlbear and the beholder "inflicted their first damage in the dungeons beneath Castle Greyhawk, controlled by Gygax and alternate Dungeon Master Rob Kuntz" [4]. The same piece notes the demon lord Fraz-Urb'luu was imprisoned beneath it [4]. So when your party meets an owlbear in the new bundle, it is home.
Five tries at publishing one dungeon
The original was never published as Gygax ran it [3]. Everyone since has tried.
| Year | Title | Publisher | Rules | What it was |
|---|---|---|---|---|
| 1988 | WG7 Castle Greyhawk | TSR | AD&D 1e | 128 pages, "steeped in humor", with a character called the Amazing Drider-Man; fans call it the joke version [3] |
| 1990 | WGR1 Greyhawk Ruins | TSR | AD&D 2e | Blake Mobley and Timothy B. Brown; the serious treatment, 26 dungeon levels [3][5] |
| 2007 | Expedition to the Ruins of Greyhawk | Wizards of the Coast | 3.5e | Jason Bulmahn, James Jacobs, Erik Mona; revisits Greyhawk Ruins for 3.5 [3] |
| 2008 | Castle Zagyg: The Upper Works | Troll Lord Games | Castles & Crusades | Gygax with Jeffrey P. Talanian, based on his original design, not official D&D [3] |
| 2026 | The Ruins of Castle Greyhawk | Baldman Games | 5.5e | Four adventures, levels 5-10, three towers and the dungeons beneath [1] |
Castle Greyhawk has been published as a joke once, which is once more than most castles. The serious version had its own trouble: White Wolf magazine gave Greyhawk Ruins one star out of five and told readers to "Avoid this one at all cost" [5].
Thirteen levels in 1972, twenty-six by 1990. Somebody kept digging.
The 2024 Dungeon Master's Guide brought Greyhawk back as its example setting, with a gazetteer of the Flanaess and a poster map of the City of Greyhawk [4]. Legends of Greyhawk uses that setting [2], and the castle is its most famous address.
How to find what the castle hides: the 2024 search rules
A ruined castle is a building full of secret doors and traps. The 2024 rules are specific about finding them. From SRD 5.2.1 [6]:
- Say where you look. To find a hidden object such as a secret door or a trap, the GM "typically asks you to make a Wisdom (Perception) check, provided you describe the character searching in the hidden object's vicinity." Search the wrong room and "a Wisdom (Perception) check won't reveal the object, no matter the check's total" (p. 12).
- Passive Perception is 10 plus your Wisdom (Perception) bonus, and the GM uses it when you are not actively looking (p. 22).
- The Search action is a Wisdom check to "discern something that isn't obvious" (p. 187).
- The Help action gives an ally Advantage on their next ability check with a skill you are proficient in (pp. 182-183).
Take a level 5 character with Wisdom 14 and proficiency in Perception: +5, Passive Perception 15. Here is how often they find a hidden door at each DC [7]:
| DC | Passive 15 notices it? | One Search roll | Search with Help (Advantage) | Four characters each roll once |
|---|---|---|---|---|
| 10 | yes | 80% | 96% | >99% |
| 15 | yes | 55% | 80% | 96% |
| 18 | no | 40% | 64% | 87% |
| 20 | no | 30% | 51% | 76% |
| 22 | no | 20% | 36% | 59% |
| 25 | no | 5% | 10% | 19% |
Two things jump out. Passive Perception catches everything up to its number and nothing above it, so a DC 20 door is invisible to a party walking past. And one Help action turns a 30% roll into a coin flip, 51%. Four people searching get further, but only if the GM lets everyone roll, and each search takes time the castle's wandering residents are also using.
Bring light. A Torch costs 1 CP, burns for an hour, and gives Bright Light for 20 feet and Dim Light 20 feet beyond [6]. Four four-hour sessions of dungeon is 16 torch-hours, 1.6 SP [7]. The Light cantrip is cheaper still, and Find Traps exists for a reason.
Why a dungeon full of closed doors keeps pulling you in
Loewenstein's information-gap theory says curiosity rises when we notice a gap between what we know and what we want to know [8]. A dungeon is built from gaps: a closed door, a stair going down, a map with the edge still blank. Every room answers one question and opens two.
Kang and colleagues measured it. People read trivia questions in a brain scanner and rated their curiosity. Higher curiosity went with activity in the caudate, a region tied to expected reward, and they spent scarce tokens or waiting time to learn the answers. Curiosity also predicted better recall of surprising answers one to two weeks later [9].
Here is the useful part for a DM: the pull comes from the gap, not the prize. A door the players know is there, and can't yet open, does more work than a treasure room they walk straight into. Castle Greyhawk has lasted fifty years on that. Twenty-six levels is a lot of unanswered questions.
Should you run The Ruins of Castle Greyhawk at home?
Yes, if your group sits between levels 5 and 10 and likes old-school dungeon crawling. Each Legends of Greyhawk adventure runs two to four hours [2], so four of them give a group that meets weekly a month of dungeon. If your table played Expedition to the Ruins of Greyhawk in 2007, expect the same castle rebuilt for the 2024 rules, not a sequel; the listing does not say more than that yet [1].
Table Talk
Rohan: Five versions of one dungeon. Pick one and stop.
Arthur: Two of them weren't even trying to be the same castle. One had the Amazing Drider-Man.
Rohan: And the serious one got one star. So the joke version's winning.
Arthur: The numbers are what matter. Passive 15 walks past a DC 20 door every time.
Rohan: Then my tip: whoever has the best Perception searches, and someone always takes Help. 30% to 51% for one action.
Arthur: Mine: say where you look. The 2024 rules don't let a good roll find a door in the wrong room.
Rohan: Fine. Four adventures, one level. I can do that sum.
References
- D&D Beyond. "Q4 2026: Partnered Content Release Schedule." 2026. https://www.dndbeyond.com/posts/2235-q4-2026-partnered-content-release-schedule
- D&D Beyond. "Legends of Greyhawk." Official campaign page, accessed 29 September 2026. https://www.dndbeyond.com/en/legends-of-greyhawk
- Wikipedia. "Castle Greyhawk." Accessed 29 September 2026; citing Gygax, G. (1975), Europa; Mobley & Brown (1990), Greyhawk Ruins; Bulmahn, Jacobs & Mona (2007); Gygax & Talanian (2008). https://en.wikipedia.org/wiki/Castle_Greyhawk
- Roy, J. "Greyhawk Returns in the 2024 Dungeon Master's Guide." D&D Beyond, 21 October 2024. https://www.dndbeyond.com/posts/1834-greyhawk-returns-in-the-2024-dungeon-masters-guide
- Stevens, L. "Capsule Reviews: Greyhawk Ruins." White Wolf No. 24 (Dec 1990-Jan 1991), p. 32; via Wikipedia, "Greyhawk Ruins." https://en.wikipedia.org/wiki/Greyhawk_Ruins
- Wizards of the Coast. System Reference Document 5.2.1. 2025. CC-BY-4.0. "Playing the Game" (Finding Hidden Objects, p. 12); "Character Creation" (Passive Perception, p. 22); "Equipment" (Torch, p. 100); "Rules Glossary" (Help, pp. 182-183; Search, p. 187). https://media.dndbeyond.com/compendium-images/srd/5.2/SRD_CC_v5.2.1.pdf
- DnD Dice Roller. Castle Greyhawk odds script: d20 + 5 against DC 10-25, exact; Advantage as two rolls; four searchers as four independent rolls; Legends of Greyhawk adventures per level from the campaign guide; torches at 1 CP per hour. 2026.
- Loewenstein, G. (1994). The psychology of curiosity: A review and reinterpretation. Psychological Bulletin, 116(1), 75-98. https://doi.org/10.1037/0033-2909.116.1.75
- Kang, M. J., Hsu, M., Krajbich, I. M., Loewenstein, G., McClure, S. M., Wang, J. T., & Camerer, C. F. (2009). The wick in the candle of learning: Epistemic curiosity activates reward circuitry and enhances memory. Psychological Science, 20(8), 963-973. https://doi.org/10.1111/j.1467-9280.2009.02402.x
