Cheat mode:
Enter your name as one of the following to activate the corresponding cheat function: NOTE: Some codes may only work on the U.S. version while others on the U.K. version. You may first have to enter your name as GOURANGA before other codes will work properly.

Code - Result:

yakuzadeath = God Mode
rsjabber G= od Mode
livelong = God Mode (Can Still Be Arrested)
blastboy = All Weapons
navarone = All Weapons
losefeds = No Police
desires = Maximum Wanted Level
highfive = 5x Multiplier
segarulz = 10x Multiplier
bigscore = 10 Million Points
beefcake = Increased Brutality
gorefest = Increased Gore
iamasucker = All Levels, Weapons; God Mode
coolboy = Increased Cash
muchcash = Increased Cash ($500000)
forallgt = All Weapons
godofgta = All Weapons and Ammo
bemeall = All Cities
ukgamer = All Cities
elvis is here = No Police
meatman = Hamster Runs Across Screen
itsallup = Level Select
no frills = Debug Basic Scripts
eatsoup = Free Shopping
wuggles = Display Coordinates
tumyfrog = All Bonus Levels
cutie1 = 99 Lives
buckfast = Riot Mode
hunsrus = Invisibility
arsestar = Keep All Weapons After Being Arrested
voltfest = Unlimited Electrical Gun
flameon = Unlimited Flame Gun
lasvegas = Elvis Clan People
nekkid = Naked People
danisgod = $200,000
iamdavej = $9 Million
mademan = Respect From 3 Gangs

Power-ups:
Leave a car at the dump to receive the corresponding power-up.

Car - Power-Up:

Romero = Armor
U-Jerk = Truck Machine Gun
Michelli = Roadster Machine Gun
Big Bug = Machine Gun
Bug = Machine Gun
Z-Type = Silenced Machine Gun
Police Car = Cop Bribe
Minx = ElectroFingers
Shark = Molotov Cocktails
B-Type = Invulnerability
Taxi = Double Damage
Beamer = Flame Thrower
Schmidt = Health
Dementia = Invisibility
Aniston BD4 = Jail Free Card
Miara = Rocket Launcher

Get a police uniform:
In level 2, go to where the Z gang are found and answer one of the green phones with the mission called "Flame It". It will tell you to steal a cop car. Once you steal it, get out and you will be in a cop uniform. To stay in the cop uniform, do not finish the mission.

Taxi job:
Get a taxi, then park on the side of the road and wait. Sooner or later someone will enter the taxi and you will earn money.

News van:
The news van has a dish that always points towards the church.

Truck:
Steal a truck cab from the streets, then find a trailer parked (usually in a car park, but some are just littered about). Just reverse into it to get a very long truck that is slow and tough.

Bonus level:
Collect all the GTA 2 Shields and to play the 3.Special Level.

Getting rid of cops:
Go to the territory of what ever gang you are working for and they will shoot them for you.