The Doomsday Heist is the 20th major update for Grand Theft Auto Online. It centers around a three-act story, with each act being (essentially) one large heist mission. Each mission will require prep missions, advanced setup missions and finally the act's finale.

What the update includes.

In addition to the three new heist/story missions, the update includes:

• Choice of 9 IAA Facility Locations available for purchase (limit one per player)
• Customization options for IAA facility
• 9 New weaponised vehicles 
• The Avenger Flying Fortress  command center
• Orbital Cannon
• New Mk II weapons are available for upgrade through the MOC (Mobile Operations Center) and the Avenger
• 8 New Trophies & Achievements

IAA Facilities 

In order to begin The Doomsday Heist storyline, you must first purchase one of the nine newly disclosed underground IAA bases hidden around San Andreas. When purchasing one of these bases, players have the option of upgrading the following amenities:

• Facility Designs:
  Choose on of nine graphics to be the symbol of your base.
• Facility Style:
  There are nine different color schemes available for the abandoned IAA base.
• Lounge:
  The base comes with an employee lounge, but these areas can be upgraded with optional design styles.
• Orbital Cannon:
  This satellite-mounted superweapon can be unlocked by purchasing a War Room for your facility. Ammunition must be purchased individually.
• Personal Quarters:
  Provide yourself with a bed and wardrobe, allowing you to spawn at your base.
• Security Room:
  This addition features a gun locker to change loadouts at, as well as computer terminals to monitor the base's security cameras and also recruit a strike team of NPC soldiers to accompany you while in Free roam.

The Orbital Cannon

The Orbital Cannon, once purchased, can be used in three different ways:

• Surveillance: Players select this and are able to maneuver the Satellite cam around freely, using it to view other players or parts of the world. There is no cost associated with this option as the player cannot fire the weapon.
• Manual Targeting: After locating a viable target, this option has the player fire the orbital cannon themselves.
• Automatic Targeting: This option allows players to remotely choose a player from the session list to be tracked, targeted and fired upon by the Orbital Cannon.

Each firing charge of the cannon must be purchased individually, and there is a lengthy cooldown period before it can be used again by the same player.

The Flying Fortress: The Avenger

This aircraft is armored, heavily weaponized and able to hold up to 30 players inside it at once. It can be placed into "hover" mode to allow the pilot to get up and walk around the interior of the aircraft.