There are hundreds of add-ons: new campaigns and units primarily, plus downloadable units and building from various sites.
I love this game. still play it often. I do have one complaint, though: the super Kbots really just turned the game into a rush to see who could build the biggest badass death machine first. Especially when the Karganeth was released.
The Karganeth, incidentally, was described as a demolitions Kbot. it could survive two successive nuclear strikes, and the only things in the game that could target it were big berthas (and their CORE counterpart) and missile silos. everything else was completely blown to shreds before it ever got in range to fire. as can be imagined, one Karganeth was more than enough to take down pretty much any enemy force.
and, of course, the lack of a unit cap in the game meant you could field as many of the fucking things as you wanted.
some of the units that were released alongside it, however, such as the "necro" resurrection Kbot - which converted the scrapped remains of fallen units back into functioning friendles, were really useful, as was it's ARM counterpart, the medic Kbot (no weapons, but a nanolathe that was just as powerful as the commander's, allowing it to heal any unit or building within seconds.)
love that game to death.
