Wednesday, 24 July 2013

Alertness and Stealth

I have been thinking about using a skill system in my next campaign; I was trying to come up with a couple of skills, when I got this idea. The general rule in most OSR D&D-esque games is that parties are surprised on a roll of 1-2/d6, which is essentially a d6 roll against a Target Number (TN) of 3; these numbers are hard coded, but I wanted to play with them a little, which resulted in the following:

Alertness could be a skill which decreases the chances of surprise (by increasing the die size step by step); it could be rolled against 3 by default or higher in case of stealthy creatures (5 for giant spiders lurking on the ceiling, for instance).

Stealth, on the other hand, could be a passive skill, increasing the TN the opponents have to roll against to avoid being surprised; the TN is 3 by default, 4 for skilled, 5 for expert, and 6 for master skill level.

Although noting these numbers for individual monsters seems like extra work, it is actually already included in the rules (counting the chances from 1 and up, though). Any possible downside of this I do not see? How would you try to implement such a rule?


  1. I've played around with some similar approaches. The trick though is that the surprise roll is usually an aggregate roll (one roll per group), so some finesse is required to figure out how to account for that (use the worst roll for the entire group? allow stealthy characters individual rolls?).

    1. In case of the proposed rules above, I would say a single roll by the Referee compared to the individual TNs Stealth grants, so that some party members still get a surprise round.

      As for Alertness, I see three options:
      (a) roll dice separately for each character
      (b) roll the highest die available for the group
      (c) roll the highest die available for the group but apply it individually by capping the rolled number at the highest possible result the individual character could have achieved (it would matter only for 7+ TNs, though).