Vigilante

The Vigilante mission is a vehicle-based side mission in every 3D Universe game, Grand Theft Auto IV, and Grand Theft Auto: Chinatown Wars in which the player is required to chase down and kill the indicated targets (other criminals) within a time limit. Vigilante mode can be activated at any time (when not already in a mission) from within a Law Enforcement vehicle.

Brown Thunder is an identical side mission, which can be activated from a Hunter attack helicopter in games in which the vehicle appears, excluding Grand Theft Auto: San Andreas. It can be done in place of the Vigilante. The name Brown Thunder is a reference to the 1983 action film Blue Thunder, which centers on a heavily-armed law enforcement helicopter.

Overview
At the start of the mission, a criminal spawns in a random vehicle (clearly marked and shown on the radar) and attempts to evade the player. If the vehicle catches fire or is held in place for more than a couple seconds, the occupant(s) will bail out and run or attempt to acquire new transport. They may even steal your car! In GTA Vice City, a new car will spawn for the criminals to use if the player doesn't kill them fast. As the player completes each level, the target/s come armed with better weapons and, as of Grand Theft Auto: Vice City, become more numerous until eventually, multiple vehicles appear with each new level. In Grand Theft Auto: San Andreas, criminals will have the ability to drive-by. The player has to be ready to flee as well, since some of the criminals come very heavily armed with, for example, Rugers and Shotguns that can, and will, kill both the player and their car in seconds.

Aside from the obvious choices of drive-by shooting the target vehicle until it blows up or ramming it off the road, there are other options. For example:
 * Performing the PIT maneuver to spin the vehicle out and then successfully blocking it will prompt the target/s to abandon the vehicle, allowing you to engage them in a firefight or simply run them over.
 * Identifying the target vehicle's likely route (only a practical option in some areas with few side roads) and setting up an ambush or roadblock ahead of it. Using a powerful weapon, it is very possible to blow up their car before the assailants have time to get out of it.

The mission is failed if the player remains outside of a Law Enforcement vehicle for more than 60 seconds in one go, if the player dies or is busted, and of course if the time runs out. Vigilante mode does not grant immunity from the Police, who will often pursue the player for murder, firing weapons, hitting police cars etc. They make it a lot harder since almost no emergency vehicles can be resprayed, and you might rack up your wanted level faster than you can find police bribes.

Each time a Vigilante mission is started, the player must begin at Level 1, and cannot continue a previously failed or cancelled mission. GTA Vice City Stories has a checkpoint every five levels so you can restart at that checkpoint if you failed or canceled before completion.

Rewards

 * Grand Theft Auto III
 * +1 Police Bribe at the Hideouts (Total 10 Kills in Portland)
 * +1 Police Bribe at the Hideouts (Total 20 Kills in Portland)
 * +1 Police Bribe at the Hideouts (Total 10 Kills in Staunton Island)
 * +1 Police Bribe at the Hideouts (Total 20 Kills in Staunton Island)
 * +1 Police Bribe at the Hideouts (Total 10 Kills in Shoreside Vale)
 * +1 Police Bribe at the Hideouts (Total 20 Kills in Shoreside Vale)
 * Grand Theft Auto: Vice City
 * Maximum Armor Increased by 50% (Complete Level 12)
 * Grand Theft Auto: San Andreas
 * Maximum Armor Increased by 50% (Complete Level 12)
 * Grand Theft Auto: Liberty City Stories
 * Maximum Armor Increased by 50% (Complete Level 12)
 * Grand Theft Auto: Vice City Stories
 * Maximum Armor Increased by 50% (Complete Level 15)

Vehicles

 * The following vehicles can initiate missions:
 * Barracks OL
 * Enforcer
 * FBI Car
 * FBI Rancher
 * FBI Truck
 * FBI Washington
 * HPV1000 (bike)
 * Police Car
 * Ranger
 * Rhino (tank)
 * Hunter (helicopter)
 * SWAT Tank
 * VCPD Cheetah
 * VCPD Wintergreen (bike)

Cheat
In some of the 3D Universe games, it is possible to use cheats to complete vigilante levels very quickly - despite there not being any actual cheats made directly for the vigilante gamemode.

It involves getting a police vehicle, driving it into a garage the player owns, then beginning the Vigilante side-mission. This would spawn a criminal, who is almost certain to be either inside or next to a vehicle. After leaving the garage, the player then enters in a cheat to blow up all vehicles, which would kill the criminal, but also blow up the police car; however, simply re-entering the garage would cause the police vehicle to be fixed. The player can then carry on doing this process, until they have cheated their way onto their desired vigilante level.

Bugs
A glitch exists in GTA: San Andreas that allows completion of Vigilante without actually having to engage the enemy. Trigger the sub-mission, and park the police vehicle near the entrance to a food place such as Burger Shot. When the targets are identified, exit the vehicle (a countdown clock to mission failure will begin) and enter the food place. Wait about 20 seconds and exit. If done correctly (the exact timing may vary and one must be careful not to run out of time), the game will indicate that the targets are dead. Quickly reenter the police vehicle and wait for the next mission. Repeat. On the PS2 this has been done successfully for all levels. One walkthrough reports it works on the Xbox too but only up to a certain point, and purchasing food may or may not be necessary.

Tips
The Hunter is the only helicopter that can initiate the Vigilante side-mission in the 3D Universe, and it is highly advised you use it. In GTA: San Andreas, you can unlock the Hunter in the Verdant Meadows airstrip after completing the Flight School with 100% gold medals. The main advantage of using the Hunter is the ability to stay up in the sky and not be damaged by the criminals or the police (excluding law enforcement air vehicles that appear from a 3 star wanted level and above), as this is the main factor of why the Vigilante side-mission is one of the most difficult side-missions in the game. The main strategy is only using the mounted machine-gun, as due to a bug, kills with the machine-gun are flagged as not able to gain you a wanted level. This gives you a technical immunity to the police. The machine-gun also has the ability to automatically target people/vehicles within a certain viewpoint. Coupling these advantages along with the unlimited ammunition the machine-gun carries along with it, the Hunter is the most superior vehicle you could use for the Vigilante side-mission.¹

Overview
n GTA IV, the Vigilante missions are retooled. When Niko accesses a police car, they can access the criminal database computer and view crimes in progress in the area. The player has a time limit to get to the crime scene, but once there the timer stops. These crimes include:
 * Gang activity, which involves killing a group of thugs;
 * Stolen vehicle, which involves chasing down the criminal in the stolen vehicle; and
 * Suspect on foot, which consists of only one criminal fleeing a crime scene, and are usually the easiest, as the criminal can simply be run over.

The criminals in Vigilante missions have limited ammo. If their bullets ran out, they will throw away the gun and use their bare hand to fight.

20 missions must be completed for the Cleaned The Mean Streets Achievement and for 100% completion. The 20 missions however do not need to be done consecutively. In addition, there is a new form of the mission called Most Wanted.

Rewards

 * Cleaned The Mean Streets Achievement/Trophy

Vehicles

 * The following vehicles can initiate missions:
 * FIB Buffalo
 * NOOSE Cruiser
 * NOOSE Patriot
 * Police Patrol
 * Police Cruiser
 * Stockade
 * Police Stinger ( GTA: TBoGT Multiplayer)
 * Police Bike (GTA: TBoGT Multiplayer)
 * Police Buffalo (GTA: TBoGT Multiplayer)
 * Brickade
 * The Enforcer, Annihilator and Police Maverick can be used to continue missions after they have been initiated in another vehicle.

Overview
In GTA Chinatown Wars, the Vigilante missions are retooled. When Huang accesses a police car, they can access the criminal database computer and view crimes in progress in the area. The player has a time limit to get to the crime scene, but once there the timer stops. These crimes include:
 * Gang activity, which involves killing a group of thugs;
 * Stolen vehicle, which involves chasing down the criminal in the stolen vehicle; and
 * Suspect on foot, which consists of only one criminal fleeing a crime scene, and are usually the easiest, as the criminal can simply be run over.

The side-mission automatically ends when you kill the last criminal on each wave, and to restart it you must reenter a Law Enforcement vehicle and access the Police Computer, so you don't have to beat all five waves consecutively to obtain the Gold Medal, as long as the chain is completed without failure.

Rewards

 * Maximum Armor Increased by 100% (Get Gold Medal)

Vehicles

 * The following vehicles can initiate missions:
 * FIB Buffalo
 * NOOSE Cruiser
 * NOOSE Patriot
 * Police Patrol
 * Stockade
 * Brickade
 * The Enforcer, Annihilator and Police Maverick can be used to continue missions after they have been initiated in another vehicle.

Overview
GTA V features a Bounty Hunting side-mission in place of the Vigilante side-mission.