Well, as it happens, I've been pondering running a modern/near future Planescape game, This post is an intellectual excercise of sorts, bouncing my take on the idea around. While I have nothing against the modern planescape project--it's damn good work--the project's approach doesn't really suit my style of DMing.
So, here goes.
- Technology level: Planescape works best with a slighlty higher tech feel than some of the other published settings. I know I don't feel like moron if I make my Planescape games feel more steampunky than most D&D. I think the same applies if you want a modern game--the compination of races, many smarter than regular humans should mean better technology.
- I like a cyberpunky level of tech, but less cyber and punky--more balanced, and well thought out--materials science, computing, cybernetics, weapons tech, biotech, etc. all combing in one technological soup.
- On the other hand, magic is fast and easy, especially for said smart races--technology's benefit is it's accesability, not so much it's power. This may keep the best general technology in the hands of short-lived mortals who are more inclined to use technology--outsiders, among other things would probably stick to magic, perhaps adopting modern weapons and armor
- These assumptions only work if there is some restrictions in how magic and tech interract. Metaphysical explainations can come later, but the urban planescape explaination of why guns are so hard to enchant feels sound--that is they have to be enchanted part for part--insanely complicated and expensive
- This does not exclude full magic, but a magic user may have Harry Dresden style problems when dealing with technology. It serves as a balancing factor of sorts.
- Tech is probably different than we would envision it. The planes ar not 21st century earth. We'd never see the kinds of fighter aircraft around toady on a Blood War battlefield for example--the planes we know were built for standoff range conflict and air superiority in the Cold War. Fighter planes in the Blood War would be more similar to late WWII jet aircraft: cheap, numerous, and relying on guns as their main armament, probably more heavily armored too. Consideration has to be given to this.
- Reactionary groups--especially magic users--add a new element and perhaps a new faction (or sect) as well
Tech is probably different than we would envision it. The planes ar not 21st century earth. We'd never see the kinds of fighter aircraft around toady on a Blood War battlefield for example--the planes we know were built for standoff range conflict and air superiority in the Cold War. Fighter planes in the Blood War would be more similar to late WWII jet aircraft: cheap, numerous, and relying on guns as their main armament, probably more heavily armored too. Consideration has to be given to this.
Why do you think that? Modern fighter aircraft are designed for conventional warfare, and are plenty suited to the bloodwar. Air superiority is important for both neutralizing enemyfighters, and so that your fighter/bombers and attack helicopters can wipe out enemy armor and artillery. Dropping a fuel-air bomb would be just as effective in the blood war, unless of course your opponent happened to be immune to fire 3:>. In general though, any modern piece of equipment I can think of would translate fine to the bloodwar as long as a plane did not inhibit its funciton (Any plane without air would prevent lift for example).