If you steal a Mr. Tasty Ice Cream truck and listen to the music until you hear the GTA theme you can call 'ZIT' which is the tune identifying number on your mobile as it's playing and a cheat in your phone that restores your health and body armour will become enabled.

The following list must be completed to be able to get a 100% completion.

Complete ALL 90 story and procedural missions to get 68% complete.

Complete ALL 30 car thefts to get an additional 2%.

Complete ALL 50 stunt jumps to get an additional 2.5%.

Complete ALL 20 vigilante crimes to get an additional 2.5%.

Kill ALL 30 people on the list to get an additional 2.5%.

Collect ALL 200 pigeons (flying rats) to get an additional 2.5%.

Beat friends or computers at every activity to get an additional 5%.

Find ALL random characters and complete their missions to get an additional 5%.

Excluding Roman or Dwayne get ALL your friend's special abilities and do ALL their activities to get an additional 10%.

This weapon is located at Happiness Island which means you'll need to get hold of a helicopter or boat to get there. If either of those two options aren't availabe you can always swim there. At the island go inside the first door of the 'Statue of Happiness' and there will be a security guard there with a carbine rifle. All you've got to do then is Kill him to get the Carbine rifle.

Easier said than done but if you can somehow enter a police cruiser you'll automatically get 5 shotgun shells.

If your health level is getting low then jump into an ambulance and you'll get some extra health.

Complete the 'Three Leaf Clover' mission and the ski mask will become selectable as a hat anytime in your wardrobe. This is a useful item to have if you plan on doing a robbery and don't want to be recognised.

Log into a computer at the TW@ Internet Cafe and enter the URL 'www.libertycitypolice.com' and select the 'Database' tab which is located at the bottom of the homepage and you will be able to surf the Liberty City Police department files on all the characaters in the game.

If you go to the Statue of Liberty and walk up to the 2nd level there will be a door there which you have to walk through because it doesn't swing open. When you have gone through the door the game will load for a moment and you will come out wearing a new t-shirt which will have the image of the Statue of Liberty on it.

To survive in this game you need all the help you can get and gaining the indicated amount of Friendship/Relationship status with the following people will give you the corresponding bonus.

Free Ride (Call for a Taxi):
Gain 60% friendship with Roman.

Discount Guns (Buy weapons at a cheaper price from Lil Jacob):
Gain 60% friendship with Little Jacob.

Extra Help (Gang members arrive in a car to help you out):
Gain 60% friendship with Dwayne.

Boom? (Call Packie for him to make you a car bomb):
Gain 75% friendship with Packie.

Chopper Ride (Call Bruce to pick you up in his helicopter):
Gain 70% Friendship with Brucie.

Health Boost (Call Carmen and select 'Health Boost'):
Get 80% Relationship Status with Carmen.

Remove up to 3 Wanted Stars (Call Kiki and select 'Remove Wanted'):
Get 80% Relationship Status with Kiki.

50% off for ALL Clothing Stores:
Get 80% Relationship Status with Alex.

Complete the indicated tasks to unlock the following vehicles in the game.

Unlock Rastah Colour Huntley SUV:
Complete 10 Package Delivery missions

Unlock Annihilator Helicopter:
Kill ALL 200 flying rats

When you get 100% completion in the game there is no longer an ammo limit which means you can keep firing away in a gunfight without worrying about how much ammo you have left.

Find an ATM then block off traffic in the road leading to it so cars cannot pass. Then wait for someone to use the ATM, kill them then take the money they drop. It's essential at this point that you have done a good job at blocking the roads so the ambulance can not take away the corpse.

With that said... Run a bit away from your victim and go back again and the same money should be available to pick up again... If anyone is using the ATM when you go back you can kill them too and each time you return their cash will have respawned too.

Broken down? Car on fire? Try calling 911 using your cellphone in the game, the emergency services may come and your engine will be fine again.

You can view a load of Liberty City maps as part of the game. All you have to do is us a PC with an internet connection... Like in an internet cafe then use it to go to this website:

www.whattheydonotwantyoutoknow.com

Here you get access to maps with hidden items, weapons, friend locations, pigeons and jumps.

After you meet Faustin, complete ALL 100% of his missions, before attempting Dimitri's missions, as Dimitri has you kill off his best buddy Faustin. Therefore making him unable to give you his final lot of missions and you'll be unable to get 100% completion of the game overall.

Cheers to Superblobby on the SuperCheats forums for that one.

In GTA IV cheats are activated via using the mobile phone. Try entering any of the following codes after Roman has given you his old mobile phone. This happens pretty early in the game so you don't have to wait long before you can enter the cheat codes. Once you have the phone you can enter them as often as you like.

Okay, first get out your mobile phone and press x to raise the phone higher and reveal the complete keypad then use your controller to select the set of numbers according to which cheat you want to use, after you have entered the code the cursor moves to the dial button, just press x again and if successful you will see a message 'Cheat Activated' on the screen.

It's still early days for these cheat codes, so we advise you not to save your game after you have enabled a cheat code.

Full health
Call 3625550100

Full health and ammunition
Call 4825550100

Reset wanted level
Call 2675550100

Wanted level up one
Call 2675550150

Weapons 1
Call 4865550100

Weapons 2
Call 4865550150

Change weather and brightness
Call 4685550100

Spawn Annihilator cop helicopter
Call 3595550100

Spawn Cognoscenti
Call 2275550142

Spawn Comet
Call 2275550175

Spawn FBI Buffalo
Call 2275550100

Spawn Jetmax
Call 9385550100

Spawn NRG-900
Call 6255550100

Spawn Sanchez
Call 6255550150

Spawn SuperGT
Call 2275550168

Spawn Turismo
Call 2275550147

Super Cheats are putting together a complete guide to GTA IV. You can find our work in progress here:
http://www.supercheats.com/guides/grand-theft-auto-4/

As we get further into the game we'll keep adding to the walkthrough, the first set of missions are online now.

We'll keep going until we have a complete walkthrough with all the secrets revealed. So with that said, I suggest that you bookmark the guide and check back every so often if you want some GTA IV help.