On a more serious and secular note [religion isn't for me anyway ], this is something I've suggested for the late Warp mod and later seen suggested for Forgotten Hope 2. Apparently the Warp forum is down for the count, so I'll have to write this over again. Oh well. And yes, I love writing. A lot. Yes, I know it's slightly creepy.

     Abstract
Inspired by the scene in Das Boot where the sub is pelted by depth charges, which causes a fire to break out from a 'Christmas tree' or handles and gauges, I'd love it if dynamic fires were implemented in the game, along with a system for extinguishing them. Vehicles taking damage could catch fire, and incendiary and explosive weapons could start fires if hitting flammable material. Fires would hurt people near them and produce smoke, and would, if left unchecked, spread. In the event that chemicals or certain other materials caught fire, the fumes from the combustion could be harmful to unprotected infantry units.

It'd be incredible if you were at a corvette's bridge, under torpedo attack by TIE Bombers, and all of a sudden flames shoot out of an electrical cabinet or some other 'prone-to-fire' feature of the ship. Then there'd be smoke spreading as a player rushed over with an extinguisher and took out the fire.

     Implementation
First of all, vehicles and weapons would be scripted so that they had a random chance of spawning fire objects come certain conditions. For example, a corvette could have a 20% chance of spawning a fire at some point on board when its hit points reached 90%, 60%, 30%, 10%, and 5%. A spawned fire object works as a separate object, with a random chance at a certain interval of spawning its own smaller 'child' fires. For example, every 5 seconds, it could have a 25% chance of 'spreading' this way.

The 'child fire' would start with a small flame graphic, and then grow bigger gradually. Its size could be controlled by hit points, so that it started at 5% hit points, and then gradually grew if on flammable material. As it grew, the fire effect would become bigger and bigger. Once at, say, 25% hit points, it gained a small random chance at spawning new fires on its own.

Fire objects at 80% hit points or more would also regularly spawn smoke objects, which would drift away from the fire and, like real smoke, obstruct line of sight. I don't quite know how to implement smoke being toxic if the fire burns the right kind of material, and maybe this wouldn't be such a good feature anyway. Anyway, I believe smoke to be an important part of the 'fire system', because it makes fires affect tactics a lot more. I believe fires should also affect hit points of whatever comes close to them. This'd be easier to implement.

Extinguishing of fires would work by certain 'weapons' doing damage to nothing else than fires. I imagine certain droids (anyone remember Artoo ?), as well as some classes, would have firefighting equipment. Fighting fires could easily be worth points, to encourage people to fight fires instead of slaying Rebels.  In addition, I think maybe certain materials, such as snow and metal, could have a 'barb-wire' effect which only damaged fires, so that you wouldn't have, say, huge wildfires on Hoth, or a blaze raging throughout the durasteel hangar of a Star Destroyer. Additionally, perhaps certain things such as gases and oil and whatnot could counter this, adding to hit points, so that you could have a tibanna pipe aboard a ship burst and the cloud of gas nourishing the fires. Or maybe that'd make things too complicated.

     Problems
The number one problem I foresee here is lag, especially with fires on board moving ships with interiors. I think that if the fires were not made too high-res, lag would be reduced, but I don't know how big the effect would be. Additionally, I'm not sure if players would really understand that fires could be fought, even though of course there can be tool-tips appearing when close to a fire or something.

Another problem is that if unchecked for a long time, fires could become truly big and beyond the control of players, who'd simply have to spend too much time fighting them. Imagine a fire at a control point making it impossible to reach and capture it, or a fire in your base preventing you from reaching your vehicles. I imagine there'd have to be some limit to how big fires could become. An alternative solution is some sort of 'Weapons of Mass Firefighting', but I just don't think that fits into FS. A firefighting sim, sure, implement a huge plane swooping over the forest dropping a cascade of water or red powdery stuff to extinguish flames. But in FS, it would just look... slightly weird .