So, I’ve been exploring a mansion’s basement and setting remains of overly aggressive inhabitants on fire. I’ve been careful with my fires, lighting them away from anything but brick walls and rock floors. Then suddenly I hear a smash from a room I already cleared. When I get there to check, I find out that SOMEHOW one of the pile of burning corpses set a BRICK wall on fire, which then spread it to wooden kegs, filled with amazing alcohol, which I was already planning to turn into vinegar -> acid -> ether -> anesthetic kits. Also, how can a tile with nothing, but an empty sidewalk catch fire from a nearby pile of burning corpses? And how do we even set fresh and naked corpses on fire with a lighter or a match?
https://i.imgur.com/kmavUDB.png The fire was lit where I am standing on the screenshot, the barrels were in the room to the right.
Living matter is pretty easy to set fire too, bodies would be pretty difficult, but not entirely impossible, sidewalks would be a different question… Grass in between? Maybe some micro-shreds of paper? Your guess is as good as mine, its probably something to make fires more potent in cities though…
Raid a military outpost, go to the deepest part, kill some armored zombies and set them on fire when they die. The fire would spread on METAL walls if its near 
In the game every buildings burn like paper and fire is the device of the final destruction. It was always like this, there is no exception.
I’ve suggested before that fire spread should be determined by the terrain of that tile. IE: If that wall is t_wall, it’s presumably drywall and wood and therefore should have a higher chance to burn. If the wall is t_sconc_wall (concrete) it should have a different likelihood to catch fire.
I imagine it would be a lot of work to implement something like that. Fire spread rate was also improved somewhat, maybe six months ago. I had a forum thread where I griped about it quite a bit.
Having done a lot of corpse-pile burning, I can tell you that a big pile of corpses will provide a LOT of fuel once they really get going, and the fire can easily spread out one or two tiles from the source as all that fat and meat starts to burn.
(I don’t think brick walls should be catching fire, but the roof could certainly burn.)
this is something im thinking about ever since the first time i play CDDA…
fire mechanism in CDDA is somewhat unrealistic because walls can catch on fire easily even if its made from material that is actually hard to burn in real life, plus corpse burning is too easy, just activate lighter and set corpse on fire. while in real-life to burn a corpse easily like that you need gasoline-doused corpse and a lighter to do that (or this could be referencing The Evil Within game mechanism where undead corpse needs to be burned with lighter to truly kill them)
but still, i love the fire capability to spread and be used as alternative crafting food, since Far Cry series i love to see fire spreading mechanism as it gives the player possible strategy and even escape plan in case of bad scenario + realistical fire hazard.
i think there should be flag for tiles like NON_BURN or HARD_BURN so that tiles with this flag will be hard to burn or not burned at all by the fires.
Rather ironic since brick is made in a kiln…with…ya know…fire >_>
Also thanks for the tip about bases. It never occured to me to set a national guard base ablaze to get rid of those damn robots.