Delta Force, or the 1st Special Forces Operational Detachment-Delta (1st SFOD-D), is a U.S. Tier One special ops counter-terrorism force and part of Special Mission Units. In Crysis and Crysis Warhead, the Delta Force, consisting of three teams, are deployed to the Lingshan Island in response to the KPA's military control over the island. During Crysis 2, Delta Force is seen through the eyes of Alcatraz during flashbacks.
The three teams, Raptor Team, Eagle Team, and Hawk Team, are deployed onto the island in response to a hostage situation in North Korean-occupied Lingshan Island. During the drop, Raptor Team is abruptly scattered by an "unknown" object and the team ends up missing the LZ. The protagonist, Nomad, and Raptor Team member Jester are then ordered by Prophet to reach Aztec's position, but came too late as Aztec was suddenly mutilated by the same "unknown" hostile. Despite the loss, Jester, Psycho, Prophet, and Nomad still continued with the mission and discovered the hostages' boat frozen inland. They also get in contact with the Ceph when a Ceph Scout breaches through the boat, snatches Jester away, and then kills him shortly thereafter. The first hostage the team rescues turns out to be a CIA agent who was sent to monitor Dr. Rosenthal's work. In the jungle, Nomad finds another hostage named Badowski dead with ice shards in his back, as the KPA battle an alien machine nearby. After Nomad regroups with Prophet, Prophet is suddenly snatched by another flying machine, which flies away with him in its grasp. Shortly after, Nomad is contacted over the radio by the American military asking if he wishes to abort the mission since most of his team has been killed or missing; Nomad refuses, saying that he can still complete the mission.
Nomad makes his way to Dr. Rosenthal's research complex, where he has found a rare fossilized artifact predating humanity by two million years. The partially excavated artifact resembles one of the flying machines (designated "exosuits") that has been attacking the team. Rosenthal also references other discoveries of similar artifacts in Afghanistan and Siberia, suggesting that the Ceph, the name of the alien race and antagonists of the game series, have a global presence, and are not just confined to the island. While Rosenthal is running a scan on the artifact, it emits a powerful energy pulse that freezes Dr. Rosenthal solid. Nomad's Nanosuit is able to maintain his internal temperature, saving his life. Nomad then rendezvouses with a VTOL, after eliminating a Nanosuit-equipped four-man KPA special forces team near the landing site. He notifies his superiors about this, because the U.S. military had hoped to prevent the Koreans from acquiring Nanosuit technology.
With the aid of the United States military, the Marines, the Air Force, and what remains of Raptor Team began their full-scale invasion on the island. As the U.S. forces advance, the mountains began to shake as one of them uncovers itself to reveal the Ceph Spaceship underneath, which is as large as the mountain itself. Nomad enters the excavation site at the mountain's base, but is captured by Kyong's men. Kyong deactivates Nomad's Nanosuit, and Nomad watches, helpless, as Kyong shoots one of the hostages in the head and then detonates explosive charges to open the structure. An energy pulse emanates from the structure and kills Kyong's men; the pulse also reactivates Nomad's Nanosuit. Kyong is also wearing a Nanosuit and attacks Nomad, until Nomad is able to kill him. As the mountain continues to collapse, a VTOL evacuates the last hostage, who is Dr. Rosenthal's daughter Helena, but is unable to rescue Nomad.
Nomad is trapped and decides to continue into the alien structure. It soon turns into a zero gravity environment. Nomad uses his hydro-thrusters to maneuver and encounters hostile sentient Cephs. He also sees a possible invasion force consisting of many ceph machines. Nomad manages to escape, but the structure creates a massive sphere of energy that freezes everything outside to -200°. Once outside, Nomad is attacked by various Ceph machines before finding Prophet. Prophet was able to engineer a weapon using the Ceph's technology, the Molecular Accelerator (MOAC). Prophet's Nanosuit is malfunctioning, and he frequently has to stop and recharge it using heat sources, such as the burning wrecks of military vehicles. The two leave the ice sphere and rescue Helena, whose VTOL crashed. Prophet leaves with Helena on another VTOL. At the U.S. evacuation point, one of the last VTOLs rescues Nomad from an unstoppable quadrupedal Ceph exosuit, which kills Major Strickland. As they leave the island, the VTOL's pilot is killed and Nomad must fly back to the USS Constitution carrier strike group, fighting off the Ceph along the way.
Once there, he is debriefed by Admiral Richard Morrison who explains that a nuclear strike has been ordered against the ice sphere. Helena warns him that the Ceph might absorb the energy, but the Admiral ignores her. Prophet flies a VTOL back to the island against orders. Despite Prophet's departure, the nuclear missile is launched at the ice sphere. The explosion causes the ice sphere to expand and prompts a massive Ceph counterattack.
Nomad is ordered to repair one of the carrier's damaged nuclear reactors. The Nanosuit is resistant to high levels of radiation, although prolonged exposure proves deadly. While Nomad is in the reactor room, Helena sends an experimental signal through Nomad's suit that causes several Ceph machines to absorb too much power and overload, destroying them. As Nomad returns to the flight deck, Admiral Morrison is killed and Nomad takes the prototype TAC-Cannon. On the flight deck, Nomad fights a Ceph exosuit similar to the one that killed Strickland. A massive Ceph warship then emerges from the sea, and Helena manages to deactivate its shields by sending a signal through Nomad's Nanosuit. Nomad then uses the TAC-Cannon to destroy the Ceph warship, which falls on the carrier and begins to sink it. Nomad runs across the flight deck and jumps off the carrier into the waiting VTOL, which is piloted by Psycho. As they fly away, Helena is nearly pulled out of the aircraft by the energy field created by the destroyed alien warship. Psycho then receives a transmission that there is another Carrier Strike Group en route to the island and suggests meeting them. Nomad protests, claiming that since they now know how to defeat the Ceph, they need to continue fighting. A transmission from Prophet, who is inside the energy field on the island, is then received. The VTOL is then seen turning around and heading back to the island.
After Psycho splits up with Nomad after the bombing of Hongzoo Harbor, he joins Alpha Company, jumps into a convoy and defends it until it is attacked and destroyed. Afterwards he and the rest of the company enter a VTOL and fly out to the other part of the island. The VTOL is shot down, forcing Alpha Company and Psycho to find a safe checkpoint. Psycho encounters a helicopter with a container after an EMP explosion that knocks him out. Psycho anyway moves out and fights his way through a beach, hotel and helps his friend Sean O'Neill and some marines in his path. Later he attacks another harbor controlled by the KPA, but is captured and tortured by a high-ranking KPA commander, Colonel Lee, who's also wearing a Nanosuit. The submarine they are onboard freezes later inside the Ice Sphere and Psycho pursuits Lee with a hovercraft to take the container. After a long pursuit, Psycho loses Lee. He instead moves on to find Eagle Team and they fight their way against the Ceph to the Pacific Shore Mine. When they reach the mine, Psycho departs from the team and fights his way through the mine. When he finally reaches the exit, he catches a train that is carrying the container. After a short ride on the train, he reaches a bridge of Ang River and tries to call O'Neill to extract the container at the bridge where it is blocked, but O'Neill does not respond and Psycho is interrupted by Colonel Lee and his men. Lee commands his men to drop the engineer, but Psycho is able to grab the engineer. However, the engineer begs Psycho to drop him so he can detonate the bridge and stop Lee, which Psycho follows. But Psycho fails and has to invade the airfield to capture the container. Psycho fights against both KPA, Ceph aliens, and a modified Hunter until he secures the airfield and extracts the container along with O'Neill back to the USS Constitution.
During the flashbacks, Psycho and the rest of Raptor Team is revealed when Hargreave discusses about the necessary sacrifices of Raptor Team, considering them as "post-human warriors". One of the only surviving members and the leader of Raptor Team, Prophet, committed suicide and transferred his Nanosuit 2 to the dying Alcatraz. Psycho survived the events before Crysis 2 and after Crysis Comic but was forcibly skinned of his suit before the events in Crysis 3.
- The emblems for the individual Nanosuit teams are modeled after the emblem of the British SAS.
- Raptor means "Bird of Prey". Both Eagles and Hawks are types of raptors.