One of the main features of this game is the ability to play the co-op mode, replacing the AI Special Ops team with players via online play. Players can play instant action missions. Players can also unlock "Character Skins" for online play.
SOCOM 4 U.S. Navy SEALs does not have lobbies like previous installments. Instead SOCOM 4 U.S. Navy SEALs has a Quick Match system along with a Party System to meet up with friends before creation of a game. The Party System was implemented in patch 1.03. SOCOM 4 U.S. Navy SEALs's Online Multiplayer comes in three forms: Standard, Classic, and Custom.
Unlike previous SOCOMs, SOCOM 4 U.S. Navy SEALs does not include many classic modes: Breach, Escort, Extraction, Control, and Convoy game modes. Instead, it features mainly all new game modes, with one classic mode, Suppression, available out of the box, and another, Demolition, available as DLC.
Last Defense: An objective-based game that requires the teams to capture all the neutral sectors placed in the middle of the map to find the opposing team's headquarters. It takes 12 seconds to fully capture a sector, and if a player dies while attempting a capture, the capture bar will remain at the same point; the player will only have to fill the bar from that point. In order to re-capture a captured sector, the team will have to fill the capture bar twice: once to remove the opponent's capture bar, and again to fill their own.
Uplink: Uplink is similar to a typical capture the flag mode. One team attacks while another defends in this game mode. The attacking team is given the task to steal the defending team's data by downloading it off random data locations set throughout the map. These data locations are shown on both teams' HUD.
Suppression: A standard team deathmatch game mode.
Bomb Squad: Similar to search and destroy mode, but with more than one bomb site. One team must protect the bomb sites while the other team must disarm them. The team that disarms the random bomb sites has one player randomly chosen as their Bomb Technician. The technician is heavily protected and armed with two unique weapons.
Demolition (DLC): An objective-based game in which a Bomb is located in a central area of the map and both teams must fight to acquire the Bomb, bring it into the heart of the opposing team's spawn area, and plant the Bomb at a designated location. Either team can acquire and use the Bomb, and there is no penalty placed on a player in possession of the Bomb. If a player carrying the Bomb is killed, the Bomb is dropped on the ground at the point in which the carrier was killed and will remain for a set amount of time for any other player to acquire. Should a player not pick the Bomb up, it will eventually respawn at its starting location. Once the Bomb has been planted in a team's HQ area, they have 30 seconds to attempt to disarm the Bomb. A team wins the round by either successfully planting and defending the Bomb until detonation, or if they disarm a Bomb that was planted in their HQ by the opposing team.
SCRUM (Custom): A Suppression mod that offers a "Classic" rules-inspired list of features that includes no respawn, no Sniper Rifles, no Concussion, Poison Gas, or Frag Grenades, higher damage and faster character movement.
Sniper Alley (Custom): Another 8-vs-8 variation on "Classic" Suppression that has higher damage values and weapon restrictions that allow players access to only Smoke and Poison Gas Grenades, Shotguns, and of course, Sniper Rifles.
Last Defense Run 'n Gun (Custom): Fast-paced deviation from the Last Defense gametype that includes speedier player movement, reduced weapon damage, and limitations to sub-machine guns and shotguns only.
Community Day Classic (Custom): Suggested by members of Zipper Community Day 2011, Community Day Classic offers a medley of different maps that support 8-vs-8 "Classic" variations on Suppression, Uplink, Last Defense and Bomb Squad with faster movement and no ranged explosives of any kind.