stevecs: yeah, basically more campaigns. I use 'dlc' as a generic as it's more content. I have Flashpoint /Urban/HM it's just that really want MORE. It just seems very little that is out there to take advantage of a good engine.
Look up the Hyades Rim mod. It is still being worked upon, but is currently 100% playable and sounds like just what you want.
The game was built as a sandbox / mercenary campaign with a bit of "choose your own adventure" aspect to it. The in-game campaign wasn't meant to be the meat of the game, but just an intro.
I'm currently playing my fourth playthrough of the game in career mode. First two were in vanilla mode. Third was with the BattleTech Revised mod. Fourth and current one is with the BattleTech Advanced 3062 mod. Will eventually do the RogueTech mod, but it was a bit overwhelming when I tried it initially. Too much tech I didn't recognize / know how to use properly.