First off: Awesome game
I recently come across this game from, of all places,
TV Tropes. I tried out the 2.2.1 build first, but found it to be a bit clunky, so I upgraded to 2.3 after browsing around the forums a bit. Then I tried to register, but there was a little hiccup (involving me somehow sharing an IP address with a spambot); fortunately, that got ironed out pretty well.
I never was a veteran of the old X-COM / UFO games, but after finding some pretty compelling reads on the
Let's Play! Archive, I was inspired to look for similar freeware games (I'm on a bit of a tight budget). I followed a link I found elsewhere on the aforementioned TVTropes, and lo and behold, now I'm converted! It runs a little slow on my comp sometimes (especially on the larger maps), but it's been pretty fun so far, although I haven't advanced very far in the plotline.
I do, however, have one suggestion: When placing new installations, I think that it would be very helpful to include a radar "shadow" for any radar-capable installations. I believe that that would take a lot of guesswork out of where to place them for max coverage of the most land surface with the fewest sites. As it stands right now, it seems like the only way you can see the coverage is after the site is already built, which of course costs money.