Shadow Ops: Red Mercury is an action-oriented first person shooter based on modern military weapons and equipment, although presented as a "Summer action movie" rather than a hardcore realistic military simulation. It is similar in feel to the Call of Duty: Modern Warfare series, although it actually pre-dates the first game in that series by 3 years. Players proceed through linear levels while battling terrorists and hostile Russian soldiers using an assortment of modern firearms.
Like many games from the time period, Shadow Ops: Red Mercury does not have regenerating health, with the player instead relying on health pickups found throughout each mission. At the beginning of each mission, the player is assigned 3 weapons (typically a sidearm, an assault rifle, and a special weapon such as a shotgun, sniper rifle, or light machine gun) and cannot obtain different weapons during the mission. The player can aim down their weapon's sights for increased accuracy (this is presented with a stylized zoom, the player still relies on the crosshair and does not truly aim down the weapon's iron sights, although telescopic sights are utilized correctly from a first-person perspective); while aiming down sights the player is unable to move, but can lean in order to fire around corners or over cover. Combat options include firing the player's held weapon, throwing grenades, and melee attacking utilizing the butt of their held weapon. One unique gameplay element is the ability to roll grenades along the floor, instead of simply throwing them through the air.
The game does not feature either a manual saving or a checkpoint saving system, each individual level must be completed from beginning to end without the player dying or quitting. However, completed levels can be re-visited at any time from the level selection menu.
Source: Wikipedia, "Shadow Ops: Red Mercury", available under the CC-BY-SA License.