So I had this idea...

Take a fortress defense scenario, kind of like Helm's Deep from LotR or a zombie enclave scenario, and do a modern version. An relatively small team, trapped inside the remains of some kind of fortification, fights a desperate battle to hold the line against the forces that have already destroyed their comrades. This would be more or less freeform, and I'd be playing, not GMing, but I guess I'd be what you call the "reality check guy." Things like the specific design, time setting, et cetera are open to suggestion, but a couple things are not. No magic. None. No non-humans. None. Other than that, roles are wide open. I would think things would be more interesting if some people played on the side of the besiegers, but obviously who the attackers and defenders are will play a large part in who wants to be whom. With the settings, I'm going for enough variety that there could be challenges for both sides; ditto with the timeframes. The defender team will be all PCs if at all possible, probably around a half-dozen; I'd like an equal or slightly greater number of attackers, but you'll also get the NPC army (which is probably the element that I'll be regulating most strictly).

Possible settings--open to any additions:
Mountain enclave (Himalaya-type plateau, all times)
Mountain enclave (Masada-style desert, all times)
Abandoned city building (post-conquest, all times)
Fortified village (used to be a small town, now essentially converted into a castle, all times)
Harbor fort (near other land, all times)
Island fort (far from other land, all times)
Underground bunker (missile silo-type thing, WW2 and later)
Underground bunker (more-developed, NORAD-style, all times)
Ship (all times)
Space station (Vietnam and later)
Provisional but unlikely because it's implausible: Something that flies (???)

Possible timeframes--also open to additions:
WW1 era: semiautomatic rifles, primitive machine guns, chemical weapons, primitive tanks
WW2 era: semiautomatic rifles, reliable machine guns, reliable tanks, minimal air support
Vietnam era: primitive assault rifles, reliable machine guns, reliable tanks, minimal air support, reliable air transport
Modern era: reliable assault rifles, excellent machine guns, excellent tanks, reliable air support, reliable air transport, specialty weapons
Postmodern era (2020-ish): basically Modern era with better/different specialty weapons. No laser guns. And NO MECHA.
Steampunk: I'm really, REALLY skeptical about even trying this, because it's hard enough to understand how the stuff we do have works, let alone steam-powered autogyros; I anticipate a pretty good technical understanding of what you're using being helpful (though certainly not mandatory, so don't let that scare you off!).
Cyberpunk: Also really skeptical; see under Steampunk.

A note on vehicles: any vehicles to which the defenders have access will be disabled, but that's not to say you couldn't jury-rig some pretty interesting defenses with what's left; the defenders will most likely never have access to air support. To balance this, if air support is available to the attackers, it will be limited to strafing runs: it is imperative that you capture the fortress rather than just bombing it off the face of the Earth.

So, fire away! Anyone interested? Anyone have thoughts on how to make it better? If there's some interest and we can settle on setting and timeframe I'll post a character template.

Wow, sounds wonderful, like always your games are! ^__^ I'm def. interested.

lol, like my games always are? i joined last week...

Anyway: if anyone who's interested would post their top 3 settings and timeframes so I can gauge which ones are likely to work, that would be great.