The player has two primary weapon slots, a handgun slot and can carry up to ten grenades. Weapons may be exchanged with those found on the battlefield dropped by dead soldiers. Unlike later Call of Duty games, the first allows the player to toggle between different firing modes (single shot or automatic fire). Call of Duty was one of the early first-person shooters to feature iron sights in game play; by pressing the corresponding key the player aims down the actual sights on the gun for increased accuracy. In addition to weapons carried by the player, mounted machine guns and other fixed weapon emplacements are controllable by the player.
The game uses a standard health points system, with a limited amount of health reflected by a health bar. Medkits scattered throughout the levels or dropped by some foes are used to restore health when the player is injured.
Call of Duty also featured "shellshock" (not to be confused with the psychological condition of the same name): when there is an explosion near the player, he momentarily experiences simulated tinnitus, appropriate sound "muffling" effects, blurred vision, and also results in the player slowing down, unable to sprint.
As the focus of the game is on simulation of the actual battlefield, the gameplay differed from many single-player shooters of the time. The player moves in conjunction with allied soldiers rather than alone; allied soldiers will assist the player in defeating enemy soldiers and advancing; however, the player is given charge of completing certain objectives. The game places heavy emphasis on usage of cover, suppressive fire, and grenades. AI-controlled soldiers will take cover behind walls, barricades, and other obstacles when available.
Campaign
American campaign
The American campaign begins with Private Martin, a newly enlisted member of the 506th Parachute Infantry Regiment, completing basic training at Camp Toccoa in Georgia, United States, on August 10, 1942. Afterwards, the action shifts to June 6, 1944, with Martin forced to undertake a solo mission to establish a landing zone for soldiers participating in Operation Overlord. Under heavy fire, the paratroopers are scattered, leaving Martin in a mixed unit formed from various companies lead by his CO Cpt. Foley. The mission closes with Martin and his allies seizing a nearby town from German forces. In the second mission, Martin and his unit are sent to drive out the remaining Germans from Sainte-Mère-Église and disable several Flakpanzers (anti-aircraft tanks) as the events of June 6 begin (D-Day). A paratrooper is seen hanging from the town church. The third mission occurs later that morning, with U.S. forces fending off a German counterattack. The fourth mission has Martin, Pvt. Elder of the 82nd Airborne and Sgt. Moody driving from Sainte-Mère-Église to Sainte-Marie-du-Mont along highway N13 to deliver an important message, while fending off German assaults. The fifth mission, the Brécourt Manor Assault, occurs on the evening of June 6, with Martin's unit destroying German artillery positions attacking the landing force at Utah Beach. After the mission, Martin learns that his unit has been assigned to several secret missions. The first occurs in the sixth mission, with Martin participating in an attack on a secret German prison in the basement of a Bavarian manor to rescue two British officers, Captain Price and Major Ingram. He then learns from Price that Ingram had already been moved to a more secure POW camp for interrogation. Thus, the seventh mission has Martin, accompanied by Price, infiltrating the camp and rescuing Ingram in under ten minutes before the arrival of German reinforcements.
In the final mission, Martin's unit takes part in the Battle of the Bulge, successfully securing top-secret documents from a bunker and stopping an attempt by the Germans to reinforce their troops with tanks.
British campaign
The first mission of the British campaign has Sergeant Jack Evans and a unit from 2nd Ox and Bucks of the 6th Airborne Division take part in Operation Tonga. Just after midnight on June 6, 1944, the unit is dropped in Horsa gliders alongside the Caen Canal near Pegasus Bridge, Bénouville. Led by Captain Price, Evans and his troops clear the bridge of German soldiers. In the second mission, just past noon on the same day, the unit manages to hold out against an attempt by a German battalion, supported by tanks, to retake the bridge. Eventually, reinforcements from the 7th Parachute Battalion arrive and the Germans retreat.
By the time of the third mission, on September 2, Evans has been transferred to the Special Air Service or SAS. He takes part in a mission to sabotage the Eder Dam, destroying the anti-aircraft guns protecting it. During Operation Chastise the previous May, the No. 617 Squadron RAF destroyed the dam using bouncing bombs, but the Germans had been able to restore it. Following extraction by Price and Sgt. Waters (voiced by Jason Statham), the fourth mission begins with Evans fighting off pursuing German troops until Waters cuts them off by blowing up a bridge. The fifth mission sees the team arriving at a German airport to complete their escape. Evans uses an anti-air gun to cover Price and Waters from
