"Damage Incorporated is a first-person shooter which incorporates a number of real-time strategy game mechanics.
The game is set in the modern-day world, and the player is cast as a Marine Corps sergeant in charge of a team of thirteen Marines. They are sent on a long sequence of covert missions, fighting various rogue militia and paramilitary organizations based in assorted locations around the United States. The player takes up to four squad members on each mission, and though they are not always required to use them, the missions become significantly easier if they do. Squad members are extremely chatty and have well-defined personalities. They can die during combat, resulting in the player potentially being short one man for the later missions.
The game also includes a separate multiplayer game, where players can each have their own squad." --MobyGames.com
Note: This is the full CD version, including intro music and all the radio voices. Includes MaraDamage, a utility that makes the Damage Incorporated maps compatible with Marathon 2 and Marathon Infinity.
The second link is the demo.