Another thing that I'm quite interest at is the possibility of having more climate factors besides Fog. An obvious choice are Rain and Snow - so a feature request would be to add a particle system (that could be simply random spawining of selected sprites) and could work as a sector special (things like gravity resistance (the way the snow flakes move along the wind and fall slowly), falling speed, density (number of sprites spawned at a certain point) and angle (random, change X angles (max) every Y seconds, or simply 90

Believe it or not, KA actually has this working somehow, it's not very difficult to do, you only have to create a "projectile" thing that doesn't does any damage just "explodes" when contacted, and spawn it with gravity by using ACS scripts in the map where you want to use it, the engine does the rest <!-- s;) --><img src="{SMILIES_PATH}/icon_wink.gif" alt=";)" title="Wink" /><!-- s;) -->, it wasn't difficult to implement at all, but the only thing left would be that the engine could do this automatically (without the need to place hundreds of mapspots to spawn the snow flakes or rain and having to write a script for it).

Thats EXACTLY the point of having a function (or sector special) to control it - thinking of natural maps (with 90% or more of outdoor areas and organic terrain) the amount of Things inside a portion of those maps would be titanic and make it simply impossible to bet on detail. Any feature capable of making the process automatic is a necessity.