Lambda Wars (formerly Half-Life 2: Wars) brings the struggle between the human resistance and their Combine overlords to a multiplayer real-time strategy setting. The Lambda Wars beta only requires Alien Swarm installed to play. It features 3 multiplayer game modes: Sandbox, Annihilation and Overrun, showcasing the Rebels and Combine playable factions and a full-fledged RTS interface and HUD. There is also a singleplayer tutorial and a handful of singleplayer missions.
December 21 patch news: with the new wars_player_setup entity and PLAYER_SETUP_APPLY_AT_START flag one can set color and faction for the CPU player in singleplayer, so that it uses correct fortified control point models.
Also take a look at the new bridge framing ;)
Fancy as ****!