Converting D&D modules to GURPS (quickly)

[sjmdw45]

Someone asked me in a PM about how I convert D&D Dungeon Crawl modules to GURPS, and perhaps I should also post my guidelines here. My main goal is to be able to run GURPS adventures straight out of the D&D booklet--I may convert some monsters in advance for convenience but I should be able to do it in my head if necessary.

For required skill rolls, DC 15 is an unpenalized roll vs. a relevant attribute/skill in GURPS. Every +2 to DC is a -1 penalty in GURPS. Note that this means a GURPS character with Per 10 operating off of a Traps default (from memory, I think that's a -5 default) has 50% odds of detecting a DC 5 trap. In practice, many PCs will have Per higher than 10 and/or points in Traps so I think this is okay. Sometimes D&D modules give extra information about monsters on high DC rolls, and the same guidelines apply here: every 10 extra DC is 5 points on GURPS rolls. Obviously there will be some cases where the D&D rules just don't fit--where it's obvious that they're trying to shoehorn something into the D&D ruleset that would be more naturally done in GURPS--and in this case I ignore the D&D stats.

For the monsters, my basic rules of thumb so far have been:

1. Take basic stats St/Dx/Con/etc. ST = St. DX = 5+Dx/2. IQ = 5+Int/2. Will = 5+Wis/2. Per also = 5+Wis/2. HT = 5+Con/2. Cha I haven't done anything with so far but it would be on the order of +1 reaction bonus per +2 Cha over 10, or vice versa if Cha is under 10.

2. For each 1 HD of the monster, it gets either 1.) +1 to ST, 2.) +2 to HP (note that +1 to ST includes +1 to HP so this is really only trading 1 ST for 1 HP), or 3.) 4 points in a combat skill.

3. For every 5 HD, it gets either 1.) +1 to DR, 2.) +1 HT, or 3.) +2 ST.

4. DR = (flat-footed AC - 10) / 2. If touch AC is better than 10, give 1 level of Enhanced Parry, Dodge, or Block per 2 points of AC (depending on the monster which it will take), or else it can buy Combat Reflexes for 3 points of AC.

5. Skills (non-combat), again, get +1 in GURPS per +2 in D&D. I suppose I should subtract out the D&D ability bonuses first to figure out how many "real" plusses the monsters have in stats, but so far I haven't.

The important thing to me is not exactly fidelity to the exact toughness level of the D&D monster. Some monsters will be relatively weaker in GURPS stats and some (like orcs) will be relatively stronger. What I want is 1.) a consistent methodology that lets me pretty much convert monsters straight across without a lot of tweaking, where I could read the GURPS stats right off the D&D page if necessary, and 2.) some verisimilitude (the right "feel") for monsters in GURPS, using the D&D stats as a guide. So a Tyrannosaur in D&D is a 20 HD beast? Okay, in GURPS it's a ST 45 beast with HT 12 and DR 1. And I'll eyeball it and add Fangs and Sharp Claws--note that I'm otherwise ignoring the listed D&D damage of attacks, since I'll compute that from its ST.

Edit: Oh yeah, and 1 gp is worth $10 in GURPS. Although gp/sp are the standard currency. I don't have clear guidelines for converting magic items. Also, corrected a mistake above.

And also, 5' of D&D Move = 1.00 GURPS Basic Move. Basic Speed is computed from HT/DX normally.

I hope that's useful.

-Max

P.S. Note that I'm trampling all over point values here. 1 ST is not equivalent to 2 HP in GURPS point terms, but I don't care.