On the topic of scorch marks made by mortars and such. Can they be scaled by the size of the Radius of the explosion instead of just being one size for all? Having them disappear or fading away after a few minutes would be nice too. Maps get kinda ugly when there's a lot of them in an area.
Scorch marks actually change the color of the terrain so they're limited to terrain grid resolution and are basically impossible to get rid of. (They originally dug craters but changing terrain geometry caused too many problems.)
I turned the crater code back on in BzE and set the depth to a small amount. Only problem i see with it is new joiners will not see the craters.
I would like to see the ground char changed to a sprite that stays on the terrain for a limited time. I'm not sure that's something you would be interested in though.
BZ originally stored permanent state for them so new joiners would see them, but that mechanism broke down after a session had been running for a while. I commented out that mechanism since it greatly simplified a few things involving game objects. (In particular, it let me generate player data keys from game object indices instead of storing the player data key separately.)
I see the appeal of BZ2-style ground sprite effects, but I'd have to save that for after 1.5.