[Zilfer]

A single die system is can be more intuitive to new players, because it's easier to determine the probability of an action's success or failure. Needing a 16+ (or 5-) on a d20 gives you a 25% chance. A +2 gives you a 10% difference.
If they've never played a system with dice pools before, the whole system of hits, net hits, thresholds, and limits will be daunting, and building a character will be more frustrating than it needs to be if they can't reasonably judge how many points they will need in a skill to feel competent.
You (probably) take these things for granted, but they're not universal.

This. Exactly this. I can attest to some RL experience in this situation. I tried to get my D&D group into Shadowrun one of the times when it was my turn to take the DM's chair, and the look on their faces when they realized that I was the only person who had nearly enough d6s was pure culture shock. Afterall, in D&D you don't really need more than 6 or so d6s unless you're a spellcaster throwing things like Fireball around, or you're a high-level Rogue doing sneak attack. When they see me with 24d6, it blew their minds.

As far as Mutants and Masterminds is concerned, I've played it in several editions, and in several different campaign types (superhero, fantasy, sci-fi). It is a very adaptable system, and you can easily apply it to many different genres. Personally, I like Hero System better, for the more tactical feel, but again, being a points-based, effects-based system, it is something you can play in many different ways. I've never understood the hate some people have for d20, except by looking at indie music snobs who reflexively hate any band that signs to a label for 'selling out' and 'going mainstream'.

Yeah most people I mention to about Shadowrun, are surprised it's played with only D6's! That's before they find out I literally have well over 100d6's and probably closer to 200. I collect a lot of dice I think look cool .

[Redhawk]

This kind of thinking is completely alien to me. I grew up in the era where it was expected to learn a new system if you were switching settings... Even if the games were made by the same company (Boot Hill, Dungeons and Dragons, and Gamma World, anybody?)

The only thing that bothers me about D20 is that it brought this strange "One system to rule them all" attitude to the forefront. D20 isn't a bad system at all, you can do some pretty awesome gaming with it, but it isn't a great system outside of the genre it was created for (fantasy).

I would up-play the strengths of other systems vs. D20. The ability to focus on increasing one or two abilities for improvement rather than an across-the-board tiny improvement. More realistic damage system, and so forth.

Also, what I would suggest is to make a deal with them. Give you three sessions with pre-made characters and if they still don't like it, fine. If they won't bother to do that, try finding an online gaming group score your Shadowrun fix.

[BetaCAV]

This. Exactly this. I can attest to some RL experience in this situation. I tried to get my D&D group into Shadowrun one of the times when it was my turn to take the DM's chair, and the look on their faces when they realized that I was the only person who had nearly enough d6s was pure culture shock. Afterall, in D&D you don't really need more than 6 or so d6s unless you're a spellcaster throwing things like Fireball around, or you're a high-level Rogue doing sneak attack. When they see me with 24d6, it blew their minds.

My group plays Hero System to the near exclusion of anything else, so a lack for sufficient d6s was never an issue. But we have one player who has declared little or no interest in ANY other system (apparently, even ones he's played before; "Why fix what isn't broken?"). The rest of the group occupies a fuzzy middleground of ambivalence or excuse-making (feigned, to some degree, I think), but I suspect I could get them to try it if I were to commit to running it as a regular or fill-in game... but since I've yet to have an opportunity to play 5E myself, I'm hesitant to do so.

Once the 5th Ed books start trickling out, I may take the plunge and try it anyway... but I may have to fall back to 3rd Ed. to ditch the UMT which I am just not okay with. 4th Ed's build point system may go over better with a bunch of Hero System vets, to give a familiar looking foothold during chargen.

Hopefully 5th will get an optional BP system (or at least a PACKS-like construction system, for people who need to associate roles with classes -- *sigh*). A less neutered/genericized set of magic traditions would be a nice plus for me, but I know better (now) than to hold my breath.

It still forces me to choose between "Shadowrun Classic", "Mexican Shadowrun", and "New Shadowrun", at the moment, though... and I'm a Pepsi drinker.

[Crunch]

I'm feeling really lucky that my group is at least willing to try just about anything. SR4 was pretty much the only exception to that I can think of (the character creation turned them off so completely they just wouldn't do it).

[$/@mm-0!]

You could always meet them middle ground and play RIFTS...*cough* I was just kidding even trying to convert it to the hero system made my head hurt. Interesting classes and setting terrible rules..

[Mirikon]

This kind of thinking is completely alien to me. I grew up in the era where it was expected to learn a new system if you were switching settings... Even if the games were made by the same company (Boot Hill, Dungeons and Dragons, and Gamma World, anybody?)

The only thing that bothers me about D20 is that it brought this strange "One system to rule them all" attitude to the forefront. D20 isn't a bad system at all, you can do some pretty awesome gaming with it, but it isn't a great system outside of the genre it was created for (fantasy).

I would up-play the strengths of other systems vs. D20. The ability to focus on increasing one or two abilities for improvement rather than an across-the-board tiny improvement. More realistic damage system, and so forth.

Also, what I would suggest is to make a deal with them. Give you three sessions with pre-made characters and if they still don't like it, fine. If they won't bother to do that, try finding an online gaming group score your Shadowrun fix.

Well, remember that especially with new gamers D&D may be older than they are now. In some ways, it is a lot like the PC vs. Everything Else argument. Sure, there are some nice points about Macs and Unix, I guess, but I know Windows, I can still sling my DOS-fu, and most things that come out are compatible with my PC, as long as the hardware is up to spec. It is familiar, and familiar means one less thing I got to worry about.

The focus vs. across the board improvement thing is something you see in the level-based D20 systems, certainly, but you might consider looking at Mutants and Masterminds. It is a point-based, effects-based system like Hero System, and the 'Power Level' just serves as a basic cap on combat effects and defenses to keep things from getting too crazy ("I have 1s in all my stats, but I can shoot an energy blast that would blow up a planet with pinpoint accuracy, and I can't be hurt by a supernova").

The suggestion of pregens is something I did do with my group. I made up several characters, and told them to give me one run. Then I'd let them transfer the XP to their new characters they made, or they could keep the ones they were using. Unfortunately, a couple sessions in, one of my players had family problems, and the game got delayed. When he came back, he wanted to do something that wasn't as grim and gritty, so it was back to slaying goblins in D&D.

[Redhawk]

I really don't care for the mutants and masterminds system as it's basically a cludge of a level-based system where there are many excellent systems already out there for super-powered campaigns that work fantastically.

I'm going to assume that you were referring to the Open Gaming License when you said D&D because, hell, I'm 41 and D&D is older than I am by at least a year (depending on how you count it).

I'll also state that I use Macs and PCs because... well, because I do. It's my belief that a broader-based pool of knowledge makes for a more well-rounded person. But that's justm y 2 cents on it.

[Iridios]

Coming to this conversation late, but my advice for introducing players to the new system is to not make them learn the system right away.  If they like the setting, ask them what kind of character they would like (including race) and make the characters for them.  IMO, character creation is the biggest hurdle to enjoying a new system. 

Also don't expect them to be able to rattle off their dice and modifiers.  Let them guide their action then you can explain how dice pools are generated. 

Don't drown them in minutiae, let them get into the action then slowly add new rules to their game.  Show them that they can do more, give them incentive to learn the rules.

As GM, be prepared to fudge the rules a bit to keep the story flowing and exciting.  Give their characters 'prizes', toys that look or sound impressive.  Allow some shots to be critical hits so the players feel that they are doing awesome things.

[Michael Chandra]

I think probability can be roughly summarized in people's minds as "d20+dicedifference, TN 13." It's a nice rough estimate of the chance of scoring more hits as attacker than the defender. If they really want to look at "can I win", that's a nice guideline. It also means you need 2 dice more to win >50%.

By the way, letting players pick Sample Characters so they can try it out, then make their own, works quite well with Missions. It lets the players see if they like the concept they wanted to play, and what they think they can dump and what they want to improve.

[Csjarrat]

played pathfinder with d20 once a few years back, didnt like it.
iirc 20 was a critical success, 1 was a crit glitch. so 1/10th of the time on a perception roll you either a) see through time and space, or b) go blind from the effort of looking

[Carmody]

For me the main issue for adapting D&D d20 system to shadowrun is the huge scale of power between fresh and experienced characters.
This is something I already do not like in fantasy settings (i.e. a lvl 10 group cannot be bothered by town militia, which limits the adventures that can be played). But in SR setting it is a show-stopper to me.
If this point can be solved one way or another, then I guess an adaptation can be acceptable, even if obviously not perfect

[Lickintoad]

played pathfinder with d20 once a few years back, didnt like it.
iirc 20 was a critical success, 1 was a crit glitch. so 1/10th of the time on a perception roll you either a) see through time and space, or b) go blind from the effort of looking

in D&D, that was true only for attacks.  Natural 1s and 20s had no bearing on skill use and saving throws apart from being what showed up on the die.  It does seem to be a common enough houserule, though.  But that's not a problem with the system.

I guess Paizo could have codified it into their rules.  I never played it.  I was fine with 4E.  If I wanted to play 3E, I'd have just gone back to 3.5.

As to the OP, I understand the reticence to learn another system.  I'm about at that point myself.  I like D20 a lot.  I find it very simple and straight-forward, and I like that.  It makes it easy to move between genres with minimal rules fuss.  And, for the record, D20 works just fine for stuff besides fantasy.  BESM, Stargate and Star Wars Saga were excellent D20 games (I consider Saga Edition the apex of D20 systems so far).  However, Shadowrun is my favorite system I've played.  I don't like GURPS, either, but I do play in a game because my friend GMs it.

Shadowrun can look very complicated.  I was lucky in that I joined a group of people who had played it before, and I was able to learn from them.  Now I'm the rules encylopedia for the group, and they all come to me with questions.  But, in reality, it's not too complicated.  And, it helps sell the setting more than any D20 variant could, in my opinion.  It's well worth attempting it.  It may be that you don't like it.  But you never know until you try it.

[Mirikon]

I really don't care for the mutants and masterminds system as it's basically a cludge of a level-based system where there are many excellent systems already out there for super-powered campaigns that work fantastically.

Um, have you ever played M&M? Because I've played M&M, Hero System, and BESM, and I can tell you that all three, with their points-based, effects-based systems, play similarly. The three have their strong points and weak points, and are thus better suited to certain types of games.

Mutants and Masterminds - Remember reading comics and seeing the freewheeling battles where Hulk throws a tank at someone, or where the X-men are in a free-for-all against a Sentinel? That's the kind of feel M&M has. Everything is more abstracted, making it good for most superhero games. Good for a wide range of characters, though some types may be a little hard to put together (it is something of a nightmare trying to put together a person who can drag someone into the digital world where your Computer skill determines your abilities, best to stat it up like a kind of dimensional movement).

BESM - The version I played was with the tristat system. As the name (Big Eyes Small Mouth) suggests, it is best for anime-style games. You can do someone like Inuyasha or Kenshin easily in this system, but someone like Iceman or Jean Grey would be very difficult, since the system isn't really able to handle that kind of range.

Hero System - Of the three, Hero System actually plays more like D&D than M&M, which is a d20 system. Rigidly enforced tactical movement and hit points, along with other consumables, make this system almost like a superhero simulator. The flip side is, of course, the metric ton of work you have to do. Want a challenge? Try making a Hero System character without a calculator, spreadsheet, or character generator. It is... not pretty.

Of the three, I prefer Hero System for a long-running game, since if I put the effort into making a character, I want it to be worth it. M&M, though, is simpler, easier to use, and I can throw together a character in under an hour. For many players, the fact that they already know 80% of the mechanics (and the ones they don't know are close enough) you have a much lower barrier to entry.

For me the main issue for adapting D&D d20 system to shadowrun is the huge scale of power between fresh and experienced characters.
This is something I already do not like in fantasy settings (i.e. a lvl 10 group cannot be bothered by town militia, which limits the adventures that can be played). But in SR setting it is a show-stopper to me.
If this point can be solved one way or another, then I guess an adaptation can be acceptable, even if obviously not perfect

I'd suggest looking at M&M. PL 8 would be 'street-level heroes' (Daredevil, for instance). Your cops/soldiers/mooks are typically PL 6 or so. The fact that damage is based on a Toughness save with increasing wound penalties (like Shadowrun), makes it so that even a bunch of mooks can seriously wound and/or kill a PL 10 character. One issue, though, is that M&M in general has a much lower lethality rate than Shadowrun does. It was designed with superheroes in mind, after all. But if you were looking for somewhere to make a conversion from Shadowrun to d20, M&M would be the place I'd start, along with d20 Future.

[SnackerBob]

The accumulated filth of all theirTHAC0 and feats will foam up about their waists and all the Bards and Paladins will look up and shout "Convert Shadowrun to d20!"... and I'll look down and whisper "No." They had a choice, all of them. They could have followed in the footsteps of good men like my father or Tom Dowd. Decent men who believed in a day's work for a day's nuyen. Instead they followed the droppings of lechers and communists and didn't realize that the trail led over a precipice until it was too late. Don't tell me they didn't have a choice. Now the whole world stands on the brink, staring down into bloodly Hell, all those OGL Apologists and Min-Maxers and Munchkins ... and all of a sudden nobody can think of anything to say.

[Elektrycerze3]

... and all of a sudden nobody can think of anything to say.

I have no idea what you're trying to accomplish here.