And since they manage to get quite a fair bit of Sci-Fi technology, why not anti-gravity units? I know this is a sort of far fetched thing, but then again, so are a lot of the weapons. (Granted we do have the technology to make most of these weapons.) Perhaps the scientist isolate a strange phenomena on the planet that is a result of the blight ridden land that creates a geo-magnetic force causing rocks to levitate, and on several dangerous expeditions into blight infested territory they get enough data to create a Geo-Magnetic anti-Gravitational engine?
Just... no. Anti-gravity sounds more Fi than Sci. It's not something I'd expect to see in the near future, or possibly anytime in the future. It just seems like gravity is too fundamentally related to mass to ever really be manipulated on a small scale for unit transportation. Magnetic levitation, yes, but that doesn't strike me as being "anti-gravity" really. I'd imagine most things dubbed anti-gravity would be more about magnetic levitation, and then all the practical systems would only work for materials that are strongly magnetic. That implies you need some sort of track, or specialized roadway for the unit to move on, as well as specialized material in the unit itself. A mag-lev train I could see, but floating, flying, gravity defying units, no.
I also don't see biological weapons being used on the last survivors of the human race. Blight weapons would obviously not be controllable. The only person who would be foolish enough to use such a weapon is someone who actually wants to kill of the human race. That just doesn't seem very Outpost like.
As for giving flying units bigger wings for the thin atmosphere, remember that bigger wings add more mass to the unit, so at the very least, this is only effective if the extra surface area gives them more lift than the extra material has mass. Sure, you could also increase their speed, but that increases fuel requirements, and the JETO thing gets into that other argument about flying around on rockets is probably not very economical. That and the air-breathing problem mentioned with conventional jet propulsion means more rocket like drives, which means more fuel requirements. I don't see such small colonies being able to keep rocket based propulsion systems operational for everyday use.
Btw, I remember reading something about the explosive units in Outpost 2 making use of TNT, which, according to the chemical reaction listed on wikipedia, doesn't seem to require an oxygen environment. However, it does state that it is more effective in the presence of oxygen due to the production of carbon. I assume this is from further combustion of the carbon?
http://en.wikipedia.org/wiki/TrinitrotolueneWhat I find interesting about these discussions, is that new units generally focus around new and more powerful weapons, or perhaps, occasionally, new armour. However, since we are talking about the last survivors of the human race, who probably don't want to blow each other up, you'd think this is the last thing they'd be doing. Perhaps they would be developing less powerful weapons, or rather more targetted weapons, that would render military units inoperable, but nor harm people, or vital structures keeping these people alive. Or better yet, perhaps there should be more non-military upgrades. Sure there is always that cargo train idea, but I think we could come up with a few more that are similar in nature. Besides, where does all that ore go in actual game play? Mostly to create weapons....