The game was one of the first non-Grand Theft Auto open world action-adventure games released after Grand Theft Auto III in 2001, and, as such, was labeled by many as a Grand Theft Auto clone, as the core game mechanics are identical to Grand Theft Auto III, and its 2002 successor, Grand Theft Auto: Vice City – the player can travel across the city freely, commandeer vehicles, do whatever they want in terms of attacking and/or killing innocent civilians, and progress through the storyline at their own leisure, spending as much time traversing the city as they wish. However, the major difference from Grand Theft Auto games is that in True Crime, the player controls a law enforcement officer. As such, True Crime has been called "the GTA III clone where you play a cop."
The game involves four main types of mission, each with their own unique gameplay; shooting, fighting, stealth and driving. In many levels of the game, even if missions are failed, the storyline will continue, sometimes with a different opening cutscene for the next level, sometimes with an alternate version of the level, occasionally by branching into an entirely different storyline.
During shooting missions, the game auto-targets the closest opponent. If the player wishes to switch target to another opponent, they must do so manually. When the player is in shooting mode, they can enter "Precision Targeting" at any time. At this point, the game switches to first-person, zooms in on the target, and goes into slow motion momentarily. While in Precision Targeting, if the targeting reticule turns green, the player can hit the enemy with a neutralizing, non-lethal shot. If the player fires when the reticule is red, the enemy will be killed instantly. Players can also take cover during shootouts, firing from behind cover when the opportunity presents itself. Players are also free to pick up any weapons dropped by enemies. Once the ammo of these weapons is depleted, however, Kang will drop the weapon and revert to his standard issue revolver, which, although it does need to be reloaded, never runs out of ammo.
In hand-to-hand combat, the player has four main attacks; high kick, low kick, punch, and grapple. After hitting an enemy a certain number of times, the enemy will be stunned, at which point the player can perform a combo by pressing a series of buttons. During stealth missions, the player is automatically placed into stealth mode. The player can approach enemies from behind and either knock them out or kill them. Bumping into objects or walking over broken glass or plastic bags will cause nearby enemies to become aware of the player's presence.
Driving missions can involve either trying to catch another car, escape from another car or tailing another car. At all times, when the player is in a car, their car's condition is shown on screen. If the car's health meter empties, the car is close to destruction. When another car is involved, that car's health meter will also be shown on-screen. When the player is tailing another car, a "Tail meter" will appear on-screen, with three sections and a moving arrow. If the arrow is in the top section, it means the player is too close and must back off. If the arrow is in the bottom section, it means the player is losing the target and must speed up. As such, the player must try to keep the arrow in the middle section as much as possible. During normal driving missions, the player can solve random crimes given by the radio dispatcher.
The player can access 24/7 facilities throughout the game to upgrade either their driving, fighting or shooting abilities. 24/7 facilities are only accessible if the player has an available "badge." Badges are earned by acquiring "Reward points"; every one-hundred reward points is converted into one badge. Entry into a 24/7 facility costs one badge, and the player must complete a challenge to earn the upgrade. If they fail, they must spend another badge to try again. Rewards points are also necessary for the player to heal themselves at a pharmacy or have their car repaired at a garage; the number of points deducted depends on the level of damage in each case. The player earns reward points for arresting or killing criminals, solving crimes and completing missions. Points are deducted for killing civilians and failing missions.
The player also has a "Good Cop/Bad Cop" meter. If the player arrests criminals, solves crimes, shoots opponents with neutralizing shots, and knocks out rather than kills opponents in stealth missions, they will get Good Cop points. If, however, they kill civilians, shoot criminals in the head, use weapons in hand-to-hand combat, or kill enemies in stealth missions, they will get Bad Cop points. At certain points in the game, the storyline will branch differently depending on whether the player has a Good Cop score or a Bad Cop score. If the player's Bad Cop score gets too high, civilians will begin to attack Kang. If the Bad Cop score reaches 99, other police, and eventually SWAT will attempt to kill him. The number of Good or Bad Cop points also plays a factor in determining the game's ending.
