Ben2 said:
Batletech could be done as a mass combat game, and would be quite interesting. It would be an absolute pain to do it with the current rules, a couple of lances a side and perhaps a tank or aircraft is the most I'd want to play at the moment, but with a faster less details system you could do full scale battles.
Actually, Mechwarrior is a credible attempt to do this. Combined arms, reasonably sized forces, the whole deal. I know, lots of people don't like clix rules, but I think they aren't so bad. They're a little simpler than what I prefer, but I had a lot of fun with this one before I finally burned out on it. (Or, more accurately, burned out on dealing with some of the regular players.)