Well, oddly enough, I've just released the Mission Generator BETA for MechaWar - a game not unlike your own, in that it is designed to allow players to field battlegroups of mechs. The game is very stripped down and tactical. It's not free. I do ask £1.00 for the game itself. But the
Mission Generator is free.
At the moment it's in beta, but we did some rigorous playtesting last night with excellent results. I'm quite proud of it.
Funnily, I'm working on a campaign system. Early days, though. I expect I'll be releasing the expanded Advanced Rules for the game, plus the second One Pound Wargame, before I get to campaigns, so I'll certainly be interested to see what you do with the idea!
R.