I've been thinking of an alien invasion type game, with a minor twist of having there be multiple independent nations not inclined to cooperate with each other, each controlled by a player. The name is pending. It's not going to be "Alien Defense", don't worry.
Each player would control their own nation's defense, and manage all the usual x-com style stuff: Research, Manufacturing, Recruiting, Combat, etc., along with negotiating with other nations. Since the players only control their alien defense programs, and not their nation, there will be a very small degree of forced diplomatic tension between all the nations (read: barely noticeable, easily passed).
Military aspects are controlled via squads - you recruit a squad of soldiers, equip them with items, watch them get more skilled, upgrade their equipment, etc.
You would also be able to 'design' (As in "I'd like to design a hover APC with energy guns using that alien tech") both air and land vehicles.
Combat is pretty simple. You choose your squads you want to send out, maybe specify a general strategy, and get a report of what happened afterwards, along with all the loot.
Time is divided into turns. Each turn you send out squads, get mission reports, research, manufacture, etc. Some missions may be multi-turn though.
Is there anyone who would join in on this (there would be limited slots) or anyone with suggestions? This is a rough outline at the moment, and I may easily scrap or refine it at any time.
EDIT: Didn't feel like bumping the topic, but the actual game should be on it's way soon-ish. Considering how prone I am to poor planning, I'm trying to flesh this one out before actually doing it.