Gamesutra is reporting
Warren Spector (Deus Ex, Thief, System Shock) is working on a new
Source engine game that will be distributed over Valve's Steam
distribution system. This is great news for gamers in that Spector is
one of the leading designers in the industry and he's going to be using
one of the best engines available. It's not good news for game
retailers as it's another game that's will probably sell better online
than it will in stores.