I'm working on a Science Fantasy Setting. Need a System

[LoA]

So I've had a weird supernova of ideas in my head, and they coalesced into a new super setting. I was primarily inspired by Planet Algol, and by the Fallout series. Basically the Nuke is never invented, instead inter-dimensional travel was stumbled upon at the end of WW2, leading into a radically different future, where the Cold War never happened. Without the intervention of potential Nuclear war, the superpowers were free to fight in a much more conventional way. This led to different cultural and technological developments. The future became much more Atom/dieselpunk, and the communist powers and capitalist powers where in a constant state of perpetual war. This led to inter-dimensional exploration for resources, and the setting up of colonies on a planet they dubbed Neo-Terra (better name coming), but little did they know that this world was fundamentally different from earth. There was a strange force flowing through the earth that the scientists on Neo-Terra couldn't quite get their heads around it.

In the year 2010, there was a disturbance and the gates that connected NT and Earth fell apart, and the colonies were left on their own. The war between the United States and Russia over Canada had escalated, but it wasn't known if the Soviet Union had discovered the means of Inter-dimensional travel. At least the Cap. Powers, and Neo-Terra had hoped so. Maybe it had something to do with this world, and it's strange physics. Whatever the cause was Neo-Terra is on it's own now. There are dragons vying to restore their civilization, the high races distrust this new human magic and will wage war to destroy it, and everyone knows that the future lies or dies with the new sciences introduced into this new world. Who controls the colonies controls the future itself.

When I thought about it, this really was the merging of all of my major setting ideas over the years. Dynama's fantasy/Dieselpunk fusion, Americans stranded in a fantasy verse, etc, etc. So I want to pursue this further. Problem is I'm having some issues. I would learn GURPS since that basically gives you everything, but I would like to stick to my system of favor 3.x/PF, but I'm having some problems with that as well. D20 Modern/Future suck. They suck, they just suck. The classes suck, and the system is just poorly presented. So if there are any better alternatives to D20 Modern/Future for 3rd edition, I would like to know.

[Steerpike]

When it comes out, I think Starfinder would be worth at least a glance on the SRD. On paper it sounds pretty much exactly what you want. You'll be ditching all of the fluff from it, but that's fine.

For a slightly older 3.X space fantasy game, you could pretty easily adapt the various Star Wars stuff. The problem here is just getting hold of it, because it wasn't released under the OGL.

[Hibou]

If you can find copies of the Alternity core rulebooks, they might better suit what you want, too. I am fond of them (although I have never had a chance to actually play a game with the system). It's heavily based on buying ranks in skills to improve your character, and the classes are just ways to reduce the point cost of buying ranks in certain skills. The two core books cover not just space opera/hard sci-fi space romps, but include rules for mutants, cybertech, and superpowers/magic ("FX"). There are usually some used copies for cheap on Amazon or Ebay.

EDIT: Note that the rule set is a bit older (it was released in 1998), and the system is a familiar, but slightly different hodge-podge of 2nd Edition and 3rd Edition rules, with a "roll under multiple thresholds" kind of resolution system. It's pretty cool, but departs a bit from what you'd probably be used to.

[sparkletwist]

D20 Modern/Future suck. They suck, they just suck.

While I certainly wouldn't disagree, I think that perhaps the problem might lie not so much with these specific systems but with the whole idea of using the d20 system in this genre. As Steerpike observed, Starfinder may be a little more suitable, but I think there are structural problems with d20 that will plague anything you try to do.

The d20 system is fundamentally designed around a "medieval fantasy" type world, and trying to integrate modern or future technology poses some real problems... which is a big part of why d20 Modern and Future suck so bad. 

Since you're doing "science fantasy," it's possible you may be able to make things fit, but only if your world follows a lot of the core assumptions that make d20 work well-- melee combat is more effective than ranged, physical strength is important, magic spells exist and can do a lot of stuff, character archetypes fit a 'class' system fairly well, and so on.

I can understand wanting to stick with a system you know well, but trying to shoehorn mechanics that just don't work for a given style of play into a given system is what created d20 Modern and Future in the first place, so I'd recommend giving it some thought.

[Steerpike]

I'd agree with sparkletwist and perhaps go a step further here and say not to worry much about a system particularly at this point, just do more world-building and figure out a system once you're actually sitting down to write adventures for a specific game with players. If at the end of it, d20 still looks like the best option, go for it. But it feels like trying to figure out a system first for a world that's pretty loosely sketched is a bit cart before the horse in cases like this, where the setting's specifics are very important.

[Weave]

I'll also echo Steerpike's sentiments to not worry too much about the system and focus more on the setting, but it's worth noting that most D20 systems (and probably other systems that aren't as "narrative-focused" like Fate or sparkle's Asura system) will force you to bend a bit of your creativity to fit the bounds of their system, unless you want to really gut it or exclude certain bits of content (or large chunks of content in more extreme cases). So in that regard you're not wrong for wanting to imagine a ruleset alongside the setting, but I would let yourself explore the space you've imagined a bit before getting concerned with the system at large.

I was going to cut out this next part because it makes my post come off as wishy-washy and noncommittal, but I figured I'd just throw it out there anyways:

I also think that a fair majority of us here (at least the more vocal members) probably err on the side of the setting over the system, and I have, in the past, used D&D's creative limitations to further spark ideas for my setting. This may not be the case for you, but I've also found value in having a setting based in a system that almost all my players wanted to play in despite my desires, and in favor of having a good time, made a 5E D&D game that was altogether pretty fun. Gauging what your players want in addition to what you want is definitely worth your time.

[Steerpike]

This may not be the case for you, but I've also found value in having a setting based in a system that almost all my players wanted to play in despite my desires, and in favor of having a good time, made a 5E D&D game that was altogether pretty fun. Gauging what your players want in addition to what you want is definitely worth your time.

I totally agree with this Weave - when you have a game to run, and your friends want to play next week, and you need to come up with something so you're not stuck with improvising everything come next Tuesday night, or whatever. This is actually basically how my current campaign setting came to be (although I've poured a lot of detail into it since) and I think it can work really well. So I'd never knock the "listen to your players and roll with the punches" style; it'd be hypocritical, for one.

On the other hand, if you don't have a group of players clamoring for a game, or time constraints, or system constraints, and you still want to world-build for a hypothetical game in the future, or for its own sake, I feel like a "setting over system" route is generally going to result in a more creative overall world, especially if figuring out a system is proving tricky. I think mucking about with systems and tinkering with mechanics can be kind of a way of procrastinating a bit from figuring out the nitty gritty details of a setting - towns, major NPCs, rivers, local cultures, languages, political tensions, religious dogmas, and all the other bits and pieces that make worlds seem real.