Developed by Bullfrog in 1993, Syndicate is an isometric real-time strategy game with a dark sci-fi theme.
SYNDICATE-Portable comes bundled with DOSbox and runs on Windows XP/Vista/7. It contains the expansion "American Revolt" with 3 new weapons, 21 new single player missions and 10 multiplayer missions.
The infamous drug control of your agents is explained in the included FAQ along with other valuable information to give you a quickstart into the game.
An interesting article in EDGE magazine describes
The Making of Syndicate.
EDIT: Download removed. The game is now available for sale from gog.com.