I played a skirmish game, and had a bit of bad luck at the beginning, and lost a bunch of my trucks. I got the message about unit limit when trying to build more. I hear the limit is 15, but if 10 get killed, can't you build 10 more? I was stuck with only 3 for the rest of the game, and had to use cyborgs. Is the limit of 15 = Trucks + cyborg engineers?