GURPS Thaarl Dungeoncrawl

Since beginning my revision of the Dungeons of Thaarl to create an Open Table megadungeon game, I’ve been messing around with some simple adaptations to the GURPS Third Edition to provide a methodology for a Dungeoncrawl game structure.

Some months ago, I worked out a procedure for the Dungeoncrawl to augment the Dungeon Fantasy Roleplaying Game, so I have further streamlined those thoughts and developed three interlinked procedures for GURPS 3e.

These notes are based on GURPS Lite Third Edition, last updated in 2003, simply because it contains rules for magic and beasts which have been removed from the latest edition. This is free to download here: GURPS Lite (Third Edition) | Warehouse 23 by Steve Jackson Games

For my actual Dungeons of Thaarl game, I’ll be using GURPS Third Edition (Revised) but I think sharing the version from our “Simple GURPS” document makes it more accessible to newcomers. Perhaps this will interest someone else out there too.


As noted before, the Dungeoncrawl requires basic procedures to run smoothly. These procedures are the Exploration Turn Sequence, the Encounter Sequence, and the Combat Turn Sequence.

Exploration Turns

The Exploration Turn is 10 minutes long. The party moves at the pace of Move x10 yards, or Move x30 feet if you prefer, as modified by encumbrance for the slowest member of the group. Periods of rest allow characters to recover 1 point of fatigue, as described in GURPS Lite page 30. Eating a meal will help recover 1 extra point of fatigue while resting.

Exploration Turn Sequence:

  1. Wandering Monsters: GM rolls 3D6 (7-), normally checked every 2 turns.
  2. Actions: The PCs decide what actions to take (movement, listening, searching, or something else).
  3. Results: The GM describes what happens. If appropriate, the GM may call for attribute or skills tests to resolve actions. If monsters are encountered, follow the Encounter Sequence.
  4. End of Turn: The GM updates time records, especially for light sources and spell durations, and the party’s need to rest.

Encounter Sequence

The PC party should assign a Leader for the moments when Encounters occur. This affects Surprise, as noted below.

Encounter Sequence:

  1. Number Appearing: The GM determines the size of the encounter, either from their notes or by rolling the optional “Number Appearing” entry in the monster description.
  2. Encounter Distance: The GM determines the distance between the party and the monsters as being 2d6x3 yards.
  3. Surprise: Each side rolls 1D, adding any modifiers (noted below), highest wins. Losers are mentally stunned.
  4. Reactions: The GM may roll for the monster’s reactions using the Reaction Table on GURPS Lite page 3. The GM is free to choose the reaction if they wish.
  5. Results: Resolve the Encounter, by negotiation or withdrawal, or by entering combat.

Surprise: Each side should roll 1D. The Leader can add +2 if they have Combat Reflexes, OR another character can add +1 if they have Combat Reflexes, but this is not cumulative. The smarter leader gets +1. Tactics skill gives +1, or +2 if the skill is higher than 20. A leaderless group is at -2 (excepting animals). The GM can apply any other modifiers as appropriate. The side with the higher score can act normally. The other side suffers mental stun, as detailed in GURPS Lite page 28.

Combat Turn

Combat is resolved using GURPS Lite pages 24-30. When combat begins, the game shifts into one action per second. At the end of combat, the party uses the remainder of the Exploration Turn (10 minutes) to rest and recover.

Combat Turn Sequence

  1. Initiative: Act in order of Move scores of all combatants, from high to low.
  2. Choose Maneuver: Active character picks one maneuver from GURPS Lite pages 24-25.
  3. Resolve Maneuver: The player and GM resolve the maneuver.
  4. End Combat Turn: When everyone has acted, the turn is over. Repeat until combat is resolved.
  5. Fatigue: At the end of each combat, characters lose ST from fatigue equal to their encumbrance penalty.

Game on!

The material presented here is my original creation, intended for use with the GURPS system from Steve Jackson Games. This material is not official and is not endorsed by Steve Jackson Games

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