How can I adapt GURPS 4e materials to D&D 5e?

Question

I have a number of GURPS resource books (of varying editions) that are amazing, containing spells, items, advantages, disadvantages, etc., but GURPS can put players off.

Is there a way to adapt these things from GURPS 4e to fit the D&D 5e system?

Answer 1

At the risk of answering the question before it has been clarified...

No.

Seriously, you have several uphill battles:

• Classes/levels versus skills and advantages/disadvantages -- leveling up is very different between D&D (leveling up gives new prescribed powers and increases hit points, generic base attack bonus, and certain saves) and GURPS (where you get extra points to add skills, stats, and possibly advantages/disadvantages).
• Roll distribution: 3d6 versus 1d20 means you'll be adjusting all the GURPS +1's based on if they are average at a skill or really good/bad. A +1 in d20 is a straight +5%, while a +1 in GURPS can range from <1% to >10% (see 3d6 vs a d20: What is the effect of a different probability curve? for a discussion about this).
• Magic system is very different -- innate powers are handled through Advantages in GURPS and spell-like abilities in D&D, and magic in GURPS is mana-based. Magic is based on spell level in D&D, and spell prerequisites in GURPS.
• Stats are on a completely different scale -- Intelligence in GURPS includes Wisdom and Charisma. A 13 in GURPS is closer to a 16 in D&D (because of the roll distribution mentioned earlier). And frankly, a 13 in GURPS means something very different than a 16 in D&D. The two really aren't comparable.
• Hit points are very different in the two systems. In D&D, it represents an abstract "I can take X amount of damage before dying" and includes intangibles like fatigue and mental wear and tear. Cite: http://www.giantitp.com/forums/showthread.php?230801-Hit-Points-Why-were-they-designed-to-be-incoherent. GURPS hit points are more self-contained.
• (added, and this is important) The whole philosophy behind GURPS and D&D is different. D&D tries to represent the heroes on a quest. Dying is difficult, people can take lots of damage and fall from massive heights, feats of strength are possible. GURPS has a much more generic approach, but it has always been based in realism. A single gut wound with a sword can kill a normal person, no matter how "high" of a level they are. Again, GURPS has ways to mitigate this realism and run in a high-heroic lens, but it's not the default mode.

You'd be better off either rewriting the supplements for D&D, building your own house rules, or having the players learn GURPS.

Answer 2

Something that might solve the problem a different way is the GURPS Dungeon Fantasy line. This is a set of supplements that use GURPS' flexibility to implement a D&D-style fantasy game. It doesn't have big settings like Eberron or Forgotten Realms, but people use D&D settings with it quite successfully.

The basic way it works is to provide GURPS character templates that take the place of character classes, to define GURPS skill usages and equipment for the Dungeon-crawling genre, and so on.

This leaves you playing GURPS, not D&D5e, but with a style of game that is basically high-powered dungeon crawl. This is the most effective way to use GURPS material in a D&D-style game, but it is a general D&D style, not specifically 5e.

Answer 3

My very limited experience runs only in the opposite direction: Converting primarily the PCs of an existing game from one version of D&D over into GURPS. (This would have been in the early 90s, so it was probably 2nd edition AD&D to 3rd edition GURPS, but I doubt this will matter.)

In that limited sense, we had some success, because the GURPS system is to some subjective degree a little more flexible and finer resolution. It is, after all, a system designed to model darn near anything, and we reasoned that we could model another gaming system with it. Note that what we did not do was try to rigidly, mechanically do some sort of batch conversion where all the characters came out balanced in the same way: E.g., if we had two fighter-ish characters (a fighter and a tough thief, by my recollection) with similar "to hit" or damage rolls, we did not try to force absolute equivalence between them, or come up with some mechanical procedure to do that. For those who knew GURPS I let them convert the characters and gave them a sanity check; for those that didn't, I converted it myself.

It kinda sorta worked in that limited regard. It was tougher convincing ourselves that the more magic-oriented classes were still converted and/or balanced, but it was playable.

Having gone through that, and having continued to play RPGs since then, I am convinced that even a light "seat of the pants" conversion from GURPS into D&D (of any edition) will not work for largely the reasons that this answer describes... but also because fundamentally GURPS and D&D are trying to do different things: GURPS is trying to provide a platform to simulate many genres, so it is not too much of a stretch to use it to try to simulate other systems. (I wouldn't try it again today, though. It worked, but not well enough to repeat the experience.) D&D, by contrast, isn't trying to do anything except be D&D-- it's not even trying to be that flexible for genre.

That is where the fundamental mechanical disconnects described in that answer come from: From completely different goals. Trying to fit a whole bunch of material from the fine-grained system of GURPS into the rigid and chunky system of D&D is not going to work well.

So my answer is basically, no: Pick and choose the best concepts that you really want to import, do some on-the-fly conversions if you must, but don't try anything rigid or mechanical. If you wanna play GURPS, play GURPS.

Answer 4

Yes, this can be done; the process is simple, straightforward, and mind-numbingly long.

In my groups, I refer to this process as "calibration".

The concept is simple, and there are even two methods. The process is grueling and often thankless, not to mention the more material exists for a given game, the time to calibrate the game fully increases seemingly exponentially:

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Method One: Literal Calibration

Start with Strength, it is the easiest. Look up the weight tables in each game, use these to build a chart of what STR in one game equals what STR in the other game. Repeat for each stat, or if the stats all use the same scale, use that to approximate all the rest of the stats.

This will lead to some approximations, but between different game systems, this is likely the closest your will get, especially for non-physical stats.

The abilities are much more difficult to calibrate, as some may simply not exist at all in the other system. Others may exist, but the normal way of acquiring them is a long process or has many requirements, which simply don't exist in the other game.

Furthermore, abilities, powers, and skills may not use the same scale, but if there are enough examples in both systems, those can be used to build an approximate conversion chart.

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Method Two: Baseline Calibration

This second method is my personal preference, but requires a very flexible and capable point buy system to be one of the systems being calibrated. Fortunately, we have GURPS. (Champions/HERO system also works).

Classes and levels are basically the same as templates in GURPS. Powers and Abilities and even Stats can all be modeled in a point buy system fairly easily.

By looking at the end result of a given effect in the target system, and then using GURPS to build the effect, we can create a chart of how many points spent on what will yield the desired end result.

So using the point buy system, such as GURPS, one creates a baseline for each system they want in the mix, and then can compare and contrast abilities using the point buy as the intermediary.

The downside is having to repeat this for every possible option in the game, or at least for every option a given character has - a mind-numbing, grueling task to be sure.

In any case, once the build-outs are all complete, you will have literally built a conversion book for the two systems. Add a third system, and using GURPS as the intermediary, you will be able to actually convert between two completely disparate systems via GURPS.

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It is worth noting that neither method will guarantee a result of a character that is legal, rules-wise, in the target systems. If you take care to build templates in GURPS that are exact matches for all the abilities that a character would receive level by level in, for example, D&D... then it can be accomplished, but expect your point totals for each package to be radically different for each level.

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In case anyone was wondering, yes, I have actually done these methods, rather often in fact. At the time, we had access to GURPS 2e and 3e, D&D 1e & 2e, RIFTS, TMNT, Heroes Unlimited, Robotech, Star Frontiers, Palladium Fantasy, and even Synnabar. We happily converted characters back and forth for use in the various campaign settings, just to see what would happen. RIFTS broke D&D rather badly, as did Heroes Unlimited to Star Frontiers, lol!

But we didn't care, as we were playing to have fun, and be silly, cool, and awesome, rather than following any sort of serious campaign arcs. Once you stat the 3 Stooges and Wile E. Coyote as superheroes, calculate how much bio-e exactly would a blue whale provide you for conversion to abilities in multiple systems, pick up a veri-tech or a Glitterboy off the black market, take on the Skesis armies and Venger plus Tiamat, and start campaigning all over multiple RPG multi-verses, movies, and book settings, all bets are pretty much off.

(Hmmm, sounds like a meme... oh right, did anyone ever take Gargamel?)

Answer 5

With great difficulty

As bryanjonker said, the systems are vastly different. Bell curve vs straight percentage, points based vs. class and level based, even low roll vs high roll. Point costs run the gamut in GURPS, while any feat or skill is roughly analogous in D&D. Is a ten point advantage in GURPS worth one feat or two feats? Even worse, some GURPS books don't even value points the same; GURPS Supers for example, is intentionally a bit (or a lot, in some people's opinions) more powerful than basic.

All that said, you can give it a try. Advantages and disadvantages could be converted into feats and flaws. You could say that 10 points in GURPS is the equivalent of one feat/flaw in D&D. With the caveat that specific advantages/disadvantages might be adjusted.

Spells are a bit harder, you have to adjust the damage from GURPS scale to D&D scale, but you also have to assign them to a spell level. Presumably that would be based on a combination of their difficulty and Magery requirements.

This would take a lot of thought and a lot of play testing to make work.

You might have better results with a more focused question. Or, (also as bryanjonker suggested), just go with one of the two systems with a handfull of house rules.