Thursday, February 13, 2014

On Jumping

For basic skill mechanics, it's not uncommon for me to turn to the d20 System (3E SRD) and abstract what I find there to some simpler rule for OD&D. Generally the SRD rules output pretty good results, but the system is far too complicated for me to use at the table (there's no way you can remember all the moving pieces, requiring constant book lookups for every bit of minutiae). So this "cutting down" process usually works pretty well for me. Here are some options for a simple running-long-jump rule (such as over pits or other obstacles):
  • Jump d20 feet; add Strength or Dex bonus, subtract −4 per encumbrance level.
  • Jump d6×3 feet; subtract −1 from roll per encumbrance level
  • Jump d4×5 feet; subtract −1 from roll per encumbrance level
You could use the first rule for more granularity and similarity to the d20 system (and it provides room for a Str/Dex bonus). The last rule is kind of convenient because it comes in increments of 5 feet per pip, matching our tabletop scale. Personally, I'm in the habit of using d6's for most everything that's not directly combat-related, so I'll be using that one. (Compare to the original d20 System rule here.)


  1. I like a system that tells players, "this is what you can expect to get automatically, and this is what you have to roll for."

    So, I've used:

    Standing jump is 1/2' per MV, roll under STR for double. Running doubles jump length. High jump is half.

    This accounts for MV speed, random chance, and the benefit of STR. It allows an unencumbered person doing a running broad 12' distance, with up to 24' with a STR check. He can high jump 3', or 6' with a STR check.

    We can assume Olympic athletes, broad jumping 29' and high jumping 8', have high STR (making it so they regularly pass the check) and are either members of an Athlete class or have taken the right feats to boost jump distance.

    Then again, what I've never appreciated before with this rule, is that my way of doing it is very swingy - on any running broad jump, you can be off by 12'. Which is weird - I expect that athletes are off by 5-10% or so on a bad jump.

    So in the end, I like your third jump roll because it syncs with 5' squares, despite having a variation of 15' between the best and worst jumps. I would give the STR modifier to the d4 roll (in my game, we're talking up to +2 for nonmagical human maximum) to bring it in line with Olympic records. I'd also say anyone trained in jumping (Acrobat class, secondary skill maybe) gets to roll twice and take the better.

    You can also get a good standing long jump roll by halving the running broad jump distance, and high jump by quartering it.

    To reduce variation, perhaps use d3+1 with STR mod? Then again is that much variation a good thing - accounting for wet dungeon floors, uneven or loose stonework, slime and mold. Imagine an adventurer who slipped and fell down a pit instead of jumping over - done in not by Green Slime but by the regular kind!

    1. I agree with all that. The double-or-nothing-more rule is pretty swingy. I think adding the STR bonus to any of those is fine, too. And at one point I also thought "really, maybe only a 3 foot jump?" and also rationalized it as a fumble, slip in the slime or cracked flagstone, etc.

  2. And yet we still lack good rule sets for jiving or wailing. ;)

    All seriousness aside, I like your simple jump rules a lot. I'd be hard pressed to decide whether d6x3 vs. d4X5 would be more useful in my current play style.

    1. Ha! Yeah, it's kind of a close call for me on which rule to pick, too.

  3. How about a d4x5, but for each +1 for STR you get to roll an extra die and take the better? Same pretty reasonable max, but stronger characters are much more likely to get close to the max. Could even say for each -1 roll and extra and take the worse... Might try that tonight if anybody does any jumping.

    1. Personally, I stay away from multiple-roll or dice-pool mechanics in my D&D games. But if you like that go for it!