Re: Converting D&D DC to GURPS Skill penalties
 

D&D also uses "everything gets harder as you level" and "everything gets easier as you level" at the same time, so it gets wonky there, too

Re: Converting D&D DC to GURPS Skill penalties
 

Thanks for all the suggestions, I'm glad that the eyeballing "system" I'd worked out is basically what others came up with, too. I know that the two systems are quite incomparable (it's not just that d20 is linear, it's that the underlying theory behind what the roll is *doing* is completely different).

Re: Converting D&D DC to GURPS Skill penalties
 

Exactly, like Bruno pointed out, there are different underlying assumptions on the relative dificulty level, the time it takes to try something, etc...
The take 10 or take 20 options (I'm rusty in D&D never played it more than once or twice) are good examples of how mechanics work differently. In D&D taking more time can garantee sucess. And a mildly challenging task can become automatic if you're skilled enough. In GURPS, extra time will get you a bonus to your chances, and no matter how skilled you are, there's allways a possibility of failure.

The length of the turn alone can make a big difference, it turns GURPS Stench spell, into D&D Death Cloud (or something, like I said, it's not my native system).

There's also the genre differences, such as the assumed level of heroism and realism. The system's assumptions on what constitutes a decent rate of sucess. In GURPS, beggining characters can be very skilled at their knowledge and skill niches, in D&D they invariably suck (skill level limits).

Re: Converting D&D DC to GURPS Skill penalties
 

Yes, this is one of those things about which I had to make peace with myself in DF. Being a complete purist about old-school dungeon RPGs would have meant starting the PCs out at 75-100 points with numerous definitive skills in the 8-12 range. But being a complete purist required me to allow many abilities -- like being able to start out as an undead-turning cleric with spells, a gigantic thug with twice human damage-taking capacity, a monk whose fists equal weapons, or a wizard -- that wouldn't fit into 75-100 points and leave much for the traditional "couple of good attributes, couple of okay ones." And by upping the points and acknowledging that it's customary to start out with decent attributes, I immediately made skill levels quite high because of what GURPS assumes about skills.

My experience led me to conclude that, contrary to what many expect, attribute levels, feats, and spells -- even epic ones -- are the easiest thing to adapt. Skills are the real challenge, because they're kind of second-class abilities in D&D while they're the core of a GURPS character. In the end, this makes conversion difficult or impossible. I think it's better to come up with an abstract concept and build an entirely new PC that fits than it is to try to convert specific traits.

Re: Converting D&D DC to GURPS Skill penalties
 

It also fits with my assumption that you can half a D&D bonus/penalty to get a GURPS one (based on D&D's rule of thumb that a basic advantage or penalty is +-2, and GURPS' assumption that the same is a +-1). Thus, I'd say DC15 = +0, halve the difference from DC15, and round in whatever direction suits your mood.

Re: Converting D&D DC to GURPS Skill penalties
 

Only for adventuring use. A 1st level smith with an assistant or masterwork tools can reliably turn out masterwork tools and weapons if they have Int 12+. A 2nd level one, or a 1st level one with tools and assistant doesn't even need the above average Int. The same applies to most other non-adventuring tasks, and in this D&D isn't very different from GURPS, where a 'professional' level of skill (about skill-12) does fine for normal activities, but feels pretty marginal when out adventuring.

Re: Converting D&D DC to GURPS Skill penalties
 

I disagree... there are level requirements for skill, therefore you have to package your skill expertise with other, mostly combat related abilities, that a smith would not gain by default over his carrer.
Why is the old blacksmith that can make incredible items any better at combat, at resisting poisons, or pretty much everything else that's not related to blacksmithing?
Besides, I was refering to the high DC rolls that can only be done by higher-level characters, when GURPS specialists can be very high-skiled, pretty much independently of point-value, as long as you have enough for that one skill.
In D&D if you can't reach that target number, it's impossible, in GURPS you can allways try...

Re: Converting D&D DC to GURPS Skill penalties
 

I was responding to statements that low level characters have poor skill levels. This is not so, for non-adventuring tasks, and even for some adventuring checks.

He's probably not, seeing as even DC25 items, about as high as a normal check ever gets, can be managed by an Int 12 guy (+1) with Skill Focus (+3), MW tools (+2), an assistant (+2) and 7 ranks = +15 automatically using 'take 10', and that's all of 4th level.

And if they're low point characters specialists like that will die like flies in any sort of dungeon worthy of the name.

Not true. Once your adjusted skill drops below three in GURPS you can't succeed either. Also, in D&D you can get good enough to always succeed (there are no auto-failure rules for skills), whereas you can't do that in GURPS.

The games have different core assumptions, but if you're not looking at the very high end (points, levels), much of the stuff converts nicely with a bit of thought.

Re: Converting D&D DC to GURPS Skill penalties
 

The biggest one, IMO, is that DC is an "objective" measure of the difficulty of a task with no reference whatsoever to who is performing it. In GURPS, skill penalty is also a measure of the difficulty of a task, but it is meaningless unless it is attached to a specific character's skill - it is more "subjective." (Someone with Skill-20 is going to face a -6 penalty with a shrug; someone with Skill-10 is going to face the same penalty with soiled pants.)

The difference, if I may offer a horrible example, is something along the lines of: DC tells you how steep the hill is (and nothing else), whereas a GURPS skill penalty helps you determine how likely it is that *you* can make it to the top.

The absence of auto-failure and auto-success rules in d20 (the lack of a "1 & 20" rule) supports how DC works, while the presence of GURPS critical result rules supports how skill penalties work.

Re: Converting D&D DC to GURPS Skill penalties
 

And yet, if he wants to get better at smithing than that, bam, you run into arbitrary benefits. So master smiths that can handle DC 30 to DC 35 run into this. You can only stack so many bonuses until you can't stack any more.

Hilarious how people just can't seem to understand this very simple concept...