Rogue trader conversion

[Temennigru]

I want to GM a rogue trader game, but using the d20 system.

Does anyone here know the system enough to tell me what the stats mean in practical terms?

For example: the d20 system is based on a 20 sided dice, so a base difficulty of 10 would be average, a difficulty 15 would be hard and a difficulty 20 would be nearly impossible. A +5 modifier is average for saves, a +2 is average for ability checks and a +3 is average for attack rolls on level 1, which grows at a rate of, on average, 1 per level (not counting optimizations), which means on average a first level character would be hitting AC 13, while a 7th level character, of a maximum of 20, would be hitting an AC of 20.

Rogue trader uses a system that is very different from d20 (ability scores go from 0 to 100, and you use % dice for checks, and you compare the result to your own score in most cases, and you have the concept of "spending" XP)

[Jarmen4u]

I'm not an expert, but what I know of Rogue Trader (and most d6 dice pool games tbh), you're better off just learning the d6 rules. You can't really do degrees of success with a single roll, and since d6 pools operate on a bell curve where a d20 has a flat probability curve, you're also throwing balance out the window. I know it's not the answer you were looking for, but since nobody else has offered anything, it's the best advice I can give.

[Florian]

Does anyone here know the system enough to tell me what the stats mean in practical terms?

As with any d100 "roll under" system, you must first understand how the modifiers work and how they´ll affect a skill roll, as those carry more weight than the actual skill value. The modifier values range from "trivial" +60 to "hellish" -60. That´s important as Degrees of Failure/Success play a heavy part in determining the actual outcome of an action, more so than the actual skill roll.

It´s nearly pointless to try and model that with the standard d20 vs. DC method, as that can only ever produce binary results. You´d have to use some AD&D/Rolemaster-style tables to replicate this.

[TotallyNotEvil]

Yeah, it's a bit complicated to convert it.

Just running 40k fluff with d20 mechanics would be the neater solution I think, just make it very deadly.

[Mr Adventurer]

For the love of god man, an emulation attempt is an exercise in madness. Surely you want to use the alternate system for it's own merits? What's the point of making it emulate a system that already exists?

Anyway you could do it with d20 Future or the new Starfinder systems if you wanted.

[Grod_The_Giant]

I mean, since 20 is one-fifth of 100, you could get a rough estimate of things by dividing by 5-- a Rogue Trader skill of 70 would translate to +14 in D&D. A 60% penalty would be a -12. But I'm not sure exactly what your game plan is here. Are you looking to translate existing characters to d20? To switch Rogue Trader to a d20 base? To run a "space super-traders and psychics" game in d20?

[Swaoeaeieu]

Having recently started a Dark heresy campaign, wich uses the same system as Rogue trader, it is probably easier to learn a new system then it is to rebuild it entirely.

it took our group one session of maybe 2 hours to build characters and get the hang of the system, it looks more difficult then it is.