The players are put into one of two teams. A team of Hold Outs and a team of Attackers. The Hold Outs team's objective is to survive four real-time minutes whilst staying in one location. The Attackers' objective is to kill all of the Hold Outs.
The Attackers have unlimited lives, whilst the Hold Outs have one life each. If the Attackers managed to kill all the Hold Outs, then the Attackers win the round. If the Attackers fail to kill all the Hold Outs in four minutes, then the Hold Outs win the round.
During these missions, the Attackers are armed solely with Sawed-Off Shotguns, whilst the Hold Outs have many powerful weapons at their disposal. If a Hold Out leaves the location of the mission, they will be disqualified from the round.
There are six Siege Mentality mission in Grand Theft Auto Online, each one at a different location. They are as follows:
- Siege Mentality I: Liquor Ace in Sandy Shores.
- Siege Mentality II: The O'Neil Ranch in Grapeseed.
- Siege Mentality III: The Daisy Lee in Terminal, Port of Los Santos.
- Siege Mentality IV: The parking garage in Pillbox Hill.
- Siege Mentality V: La Puerta Apartments construction site.
- Siege Mentality VI: Chumash Historical Family Pier.
- Siege Mentality is a phrase that relates to the state of mind when one believes that they are being constantly attacked, oppressed, or isolated by the rest of the world.