Shades of Green

A bayonet, or an underbarrel launcher (or a flamethrower ) would be useful; However, you'll have to buy and carry launcher grenades, which are different from the normal hand-held grenades. And ofcourse, the aliens will have underbarrel weapons (think of a vibro-bayonet) too...

Why not let it work the other way around as well? especially if the alien bases would have automated defence turrets and/or cyberdisks, that is. This, ofcourse would require you to research alien computers, alien software/OS and advanced hacking techniques.

Heh... X-Com extorting "protection" money from countries I love the idea! X-CoMafia!

Whatever you do, PLEASE leave the WWII theme out of the game, except for perhaps a mention or two in texts. It was overdone and repeated so many times and in so many recent gmes that it's cheesy to the extreme. That said, the cold war could be an interesting thing to mention - again, don't turn this into James Bond VS the Big Bad Red Sectoids. I've watched a Russian documentary on TV today (with translated subtitles, ofcourse) about the several secret investigations that the Red Army made into the subject of UFOs in the 1980's. Now, I don't know how relaiable it is, and if is to be believed at all, but it's still a great source of inpiration for all things X-Com related. They talked about both superpowers trying to copy alien (plasma-based) technology during the last decade of the cold war, and the Rusian military concluding that UFOs were artificial (the UFOs described there had plasma shields/engines/weapons) after a very detailed investigation. They also blamed the USA trying to build a massive EMP projector in Alask as an anti-missile defence, but then again, it's not exactly accurate. But a passing mention of cold war research in a few texts will be interesting - and will give the X-Force a history of sorts and depth.

Hybrids Similar in appearance to the Mutants suggested earlier, but similar in in gameplay function to physically stronger, less-psionic sectoids (think Gillmen). Should appear on some sectoid UFOs in the mid-late game, but mostly in bases (where they're being bred) and on infiltration missions. Look like a bit larger version of the Sectoids with hair, a (very small) nose and somewhat smaller, yet still totally black eyes.

The explanation about the X-Force being called only when the local forces fail to contain the aliens got me thinking. That is, since in most cases it will take the player a few hours to land an X-Force team at the terror site, the terror site should look like a major battlezone: damaged buildings, burned-out terrain, corpses. There will be civilian survivors to rescue, ofcourse, or maybe even military/police, but the mission should look like a place where the Aliens stayed and attacked for a time.

Maybe, then, researching the Hyperwave Decoder (?) will allow you to eavesdrop on the aliens radioing back to base from their craft? or even develop a "hyperwave radar" capable of good-quality scans of enemy UFO's foe damage? Niether option was in either X-Com game, but might be interesting,