Thief in Action

Over at Playing at the World this summer, Jon posted pages from the earliest version of Gygax's "Thief Addition" (used at GenCon VII prior to publication of Sup-I Greyhawk). I think one of the great things in there is a half-page "Example of a Thief in Action" which seems to clarify some expected usage of the thief class at that time. (Not unheard of rulings, but clarifying nonetheless.) Here we see:
  1. Automatic detection of traps prior to removal attempts.
  2. Explicit note that failure to remove a trap sets it off on the thief.
  3. Play wherein the thief splits from the party, hides from a pursuing monster, and then slips into its lair to lift its treasure.
One thing that always bothers me about these scenes -- surely I'm not alone -- is that the number of successes on display for the sample thief is wildly unlikely (probabilistically) for the chances given for the class abilities. There's definitely a tension in early D&D between sort of expecting a thief to succeed on several burgling-type tests in a row, but then having the probabilities set so low that they will fail most of the time. Some people will want to revise those chances upwards, whereas my response is to mostly remove any penalties for failure (like #2 above), and to try and give very generous benefits to success.

See Jon's article here (esp. the last image with the example of play).


  1. For me the biggest problem with the Thief as written is that even if you are less harsh with the penalties for failure, the chance of success is so small and the opportunities for using the skills so much rarer than swinging a sword it seems like you could go an entire level without once succeeding. That's not very satisfying, imo.

    My current plan is to use your Target 20, but adjust everything in the same way that AC adjusts a fighter's chance to hit. That is, tasks like locks are assigned a difficulty ranging from 9 (not really locked at all, just a latch or something primitive) to 2 (state-of-the art non-magical) and those are added in to the roll. That gives a starting Thief about the same chance of succeeding against a negligible lock or easy climb as a starting Fighter has of hitting an unarmored foe.

  2. Not to be a jerk, but Jon's article is talking about Gen Con VII, the first Gen Con after the release of D&D, not GenCon I which occurred in 1968.

    1. Not sure how I glitched that up, and I do appreciate the correction, thank you. Fixed in the post above.

  3. My preference is to leave the percentages alone, but only to call for a roll if the player tries something harebrained. If they describe a reasonable or routine course of action, I let it (mostly) succeed without a roll.