2005. After many negotiations, the United Nations Nuclear Abolishment Treaty is about to be signed in L.A., celebrating what's to be named the "Global Peace Day". However, the joyous occasion is also seen by domestic and international terrorists as a soapbox for their demands, and it's up to SWAT to keep everything going as planned. As if terrorist threats are not enough, two portable nuclear demolition devices are for sale... in the L.A. area.
A tactical FPS, the player is in control of a five man strike team, and it's up to him to guide the other two-man teams to complete each mission, for a total of 16, ranging from dangerous arrests, hostage rescue, VIP escort to track and disarm bombs, while visiting landmarks of the city such as the City Hall or the Convention Center (where the E3 takes place).
To help the strike team, each officer has one of four standard-issue weapons to choose from, a sidearm and utilities such as glowsticks, C2 door breaching charges, CS gas, flashbangs and the always useful optiwand, to know what's after the corner and the Leatherman tool, to disable electronic devices and unlock doors.
One of the missions in this game includes what may be a reference to the Police Quest series which spawned the SWAT series. In the mission where the player retakes a bank from terrorists holding bank employees hostage, one of the women being held captive is listed in the mission briefing as Marie Bonds, well known to Police Quest fans as the wife of protagonist Sonny Bonds.
A version of SWAT 3 is included in the SWAT 4 pre-sell CD.