UFOPedia thankfully hosts a wealth of information on many subjects, including this one as discussed here: http://www.ufopaedia.org/index.php/Alien_Dimension_(Apocalypse)#UFO_Growth However, a problem that has frustrated me with vanilla is that after week four, many UFO's stop being produced. This can create a situation, whereby, if X-COM is particularly good at destroying UFOs, many of the alien "missions" in the cityscape stop being activated and the play becomes "repetitive" to say the least. Additionally, the Overspawn, that can only be dropped from week eight onwards may be completely circumvented as the Aliens don't appear to go on overspawn drop missions if you destroy all of the low level UFOs in the alien dimension (presumably a bug). Instead only alternating missions of Motherships and Battleships, occasionally bombers too, will just keep dropping aliens into the cityscape or destroying buildings, nothing else... In a game where i artificially created a situation to keep the low level UFOs and knocked out one or two of the big ones, i started to get VERY strange mixes of UFOs on a variety of missions. For example, Battleships with Alien Probes or scouts that would go on "Scout" missions. Bombers that came with Destroyers and proceeded to level the city; not just one building before retreating; they stayed until shot down and many other bizarre variations of the missions described here: http://www.ufopaedia.org/index.php/UFO_Incursions_(Apocalypse) (Note this list is NOT comprehensive, for example Battleships can drop overspawn yet this page says that only motherships can) The whole late game was much more fun as a result; that mix of UFOs is needed to keep the late game missions interesting! For this reason, i propose that an option is added to OpenApoc to allow the spawning of just a single UFO of the lower level types every week after week four to keep their functionality available for missions in the cityscape and allow the aliens more "choice" over which missions they can conduct. After-all, wars encourage and INCREASE in productivity, not a steady decline as the current model of UFO growth suggests... The only way of reducing UFO growth should be by destroying the appropriate building, until that point the aliens would surely be trying to ramp up production to combat an ever stronger X-COM? It would be good to know the thoughts of others on this.