Tips / Tricks:
In any level, If you find a Penetrator parked, get in it and drive it straight in the direction it is facing as fast as you can. It will give you a cool bonus, or bring you to a secret area. Also, If you are on a mission that requires you to kill several people all in the same place, get a car rigged with a bomb, and drive into the center of your target and detonate. You will get the "Psycho Bastard Bonus".
If ya wanna get through a fence get a truck or somethig you can crawl under and drive right up to the door. Get out and crawl under it and you should be able to go under the door as well. Do the same to get back. Alternitavely drive a car so the car door is touching the door to the fence and get out. Hopefully you should go into the other side.
In Heist almighty, as soon as you start out there is a street to your right walk over to it and take a car. Drive down the street until you reach the very first street you see. on that street, take a left, follow the street to the bridge, take a right onto the bridge and follow that street for a while (keep on that street) once you reach the blocked bridge, jump it and keep following that street. follw that street for a bit and on your right will be a giant metal cage containing a tank. t get the tank, run somebody over or get a cop car and drive through the yellow/black barrier. take the tank and your off. (you can also use the fire engine and ambulance too!) to fire the tanks cannon, selecet your punh while in the tank, pick up a KILL FRENZY and fire, VOILA!
To stay alive when you are on fire (via flamethrower or explosion), go to a train station and IF a train is there go on it. Wait a couple of seconds then exit the Train. You will be in perfect health!
In San Andreas, go to any car park, preferably near a busy road. Steal as many kinds of cars as you possibly can and line them all up. Make sure that a big vehicle (Tanker, Limo etc) is sandwiching the cars. Then go to any end of the line and fire a bazooka at the tanker. There should be continuous explosions and your score should go up either to 99999999 or about 54365373. Make sure you have as many cars as possible in the car park and make sure they are parked tightly together.
In 'Bent Cop Blues' in Vice City get into the car provided then go in the direction you are facing turn left at the end then carry on and take the second left. Go straight up until you come to a slight bend in the road but carry on after that. You then come to some 'huts'. One of the huts has ramps on it and you can get a bike and go up the ramps and 'fly' over to a tank.
On Manderin Mayhem, jump in the jeep and wait for the 'Peace people' run them over and get a 'Goranga'. Then get down to the car park in Ayre Valley (The love mobile carpark) Get the multiplier behind block of houses (If you want) Then wait for the same row of people to start and get them too. Your score might rise to 5 million or so. It's happened to me twice. Not exactly a certain but worth a shot! If it doesn't happen, jump in the love mobile and blow up a police car and get an extra life and no police after you.
Cheat Codes:
Code = Effect
GROOVY = All Weapons
WEYHEY = 9999990 Points
SATANLIVES = 99 Lives
EXCREMENT = x5 Multiplier
BLOWME = Coordinates
CHUFF = No Police
EATTHIS = Wanted Level Max
PECKINPAH = Armor - All Weapons - Get Out Of Jail Free Card
FECK = Liberty City Parts 1 and 2
TVTAN = San Andreas and Lib City Parts 1 and 2
URGE = All Cities Parts 1 and 2 except Vice City only 1
CAPRICE = All Cities Parts 1 and 2
TURF = All Cities
INGLOROUS = All Cities
MADEMAN = All Cities - All Weapons
THESHIT = All Cities - All Weapons Infinite - 99 Lives
BSTARD = All Cities - Lots of money - All weapons
HANGTHEDJ = Same as "BSTARD" + a funny picture at character
SKYBABIES = Small Level Select (up to "Mandarin Mayhem")