Fire, in my opinion, spreads too easily under many circumstances.
I would like to suggest that perhaps for fire:
each square adjacent to fire (per frame) have (number of adjacent flaming squares)/70 chance of igniting.
...or at least for dry grass. Perhaps use the same chance to dry out lusher grasses?
so...
0=target
#=fire
.', #', .', .## #'# #'# ### ###
,0# #0` ,0` ,0` ,0# #0` #0# #0#
',, ',, ### #,# '## ### #,# ###
1 2 3 4 5 6 7 8
fire fires fires fires fires fires fires fires
________________________________________________________________________________________________________________________________
For 1 frame ,| For 1 frame, | For 1 frame, | For 1 frame, | For 1 frame, | For 1 frame, | For 1 frame, | For 1 frame,
1.43% chance | 2.86% chance | 4.29% chance | 5.71% chance | 7.14% chance | 8.57% chance | 10.00% chance | 11.43% chance
| | | | | | |
For 20 frames,| For 20 frames,| For 20 frames,| For 20 frames,| For 20 frames,| For 20 frames,| For 20 frames,| For 20 frames,
25.01% chance | 44.00% chance | 58.36% chance | 69.17% chance | 77.29% chance | 83.34% chance | 87.84% chance | 91.17% chance
(chance is rounded)
This way smaller fires have a chance of burning themselves out, and larger fires will still spread quite menacingly across the countryside.
I would also imagine most trees would have a lesser chance of burning(being considerably denser than grass).
...
Also, on a semi related topic, i would like to see some Australian bushland style of biomes;
hot, dry, medium tree density, and mostly populated by an equivelant to a gum tree.
Gum trees drop sticks and twigs constantly, brances occasionaly, and massive branches every now and then; they also constanty drop leaves everywhere. They are also extremely !!flammible!! and occasionally burst into flame on very hot summer days. They also only seed after fires.(and most of them keep growing even though they are scorched pitch black and dont have any leaves after the fire.)
I imagine this would make for an interesting embark location with spontanious fires in the summer and the need for fires for new tree growth. (plus the elves would have to shut up and watch if you torched the entire forest)
Though I think improved fire dynamics would be neccecary for this to be a viable option for embarking. Otherwise backburning would just be burning down your own fort so nature can't do it for you.
I can just see it now... clearing an entire forest, then purposely torching everything to make the trees grow again.(while the elves are visiting)