Well, first I want to see the script that regulates the missions (assuming that there is one). I'd like to modify the lenght of time the UFOs stays in the air, their speed, their missions.
For example, AFAIK there are four kinds of mission:
Recon: fly around a little, fly away
Ground mission: fly around, reach a city or an interestin place, generate a terror/harvesting/UFO landed mission, then fly away
Retaliate: zero on a base, destroy it
Magic!: a ground mission is generated by magic without any UFO appearing
Am I right? I'd like to tweak around the missions, but I do not know where to start...