ToME WikiOrvin: An idea was posted to add fallen trees instead of rubble in some areas, which led me to thinking about other nifty things that could be done with trees. How about allowing trees to burn for a few turns before dying, when hit by fire damage? While burning, they would become a "burning trees" terrain type, which would do fire damage to anyone attempting to pass or tunnel them (and, maybe, provide light radius 1 around them). This could be used strategically to combat monsters that can pass through trees, but don't like fire. On the other hand, it could be dangerous for a player to be surrounded (for a few turns) by large swathes of burning trees while in combat, since it would not be as easy to flee. So, be careful when playing with matches!
Sirrocco: Unangband did some *very* interesting things with burning trees, burning grass, fire and smoke. (also oil, spores and flaming arrows). On the other hand, having the Spider quest turn into a raging firestorm....