Be a Cop
Arrest old ladies who have done absolutely nothing wrong using the excellent LCPD mod. It lets you play as a cop in Liberty City. You can sign up for duty at a nearby police station, grab a partner, requisition a police vehicle of your choice and then walk the beat. Incoming calls alert you to serious crimes occurring across the city. You can charge to the scene and arrest the culprit (train on your gun on them, press E to arrest them, cuff them, then call for backup to take them away), alternatively, you can ignore that and hassle everyday citizens. You can stop them, frisk them, arrest them and then taser them at will.
This one works best with patch 1.0.7, but installation's as easy as double clicking the program and letting it do its thing. Once installed, the mod won't intrude unless you want it to. Press ALT-P in-game to start it up, and press again to disable it. A thoughtful touch.
Turn Liberty City into a playground with the Simple Trainer, a user-friendly program that will let you bind cheats to keyboard shortcuts. Default settings will let you choose the time of day with alt-1 through alt-4. Alt-. will spawn a sweet ride, Alt-7 will give you a full set of weapons and the + key will activate god mode. You can bind other cheats to your keyboard by altering the .ini file. Once you're set up, you'll be able to teleport around the map and spawn objects and vehicles at will. It works with all versions of GTA 4, too.
Recruit bodyguards, become a hitman, start a gang war
Recruit passers by, give them guns and roll through the streets as one almighty posse using the Bodyguard recruiter mod. Once installed, press F3 to command a pedestrian to join your cause. It'll cost a bit of money, but once they're in your employ they'll follow you until you fire them (with F7). Their AI exceeds follower AI in a lot of big budget releases (*cough* Skyrim *cough*) in that they'll seek out vehicles and follow you and follow you if you drive off on your own.
There are a few other noteworthy script mods that give you more to do in Liberty City. The Assassination Mod lets you contact a mysterious contractor using public payphones. These voiced conversations will send you after citizens spread throughout the city. Sometimes they'll be riding around in a vehicle, and they may even employ bodyguards to keep you on your toes.
For more shady dealings, try Turf Wars. It adds new gangs that are taking control of corners across Liberty City and lets you challenge them for control. You can call up your gang and hit corners together to take the city for yourself.
Turn off all friction
Bring total chaos to Liberty City with this simple tweak. It turns turns GTA's roads into frictionless sheets of grey death. Head into your GTA folder, go into common, then data, back up handling.dat then open it up and change the wbias column for each car to a negative value. Voila, instant comedy. Drag your backed up handling.dat file back into common/data to restore normality.
Play as The Hulk, Batman, Max Payne, Agent 47 and more
Ac.Amir is responsible for some of the best alternative character models you can find for GTA 4. Characters like The Incredible Hulk above aren't just reskins of Nico's model, they have their own gait thanks to custom animation files. A bunch of characters are available in the pack linked to above including Hulk, Batman, a Spartan from Halo, Rorschach from Watchmen, Lee from The Walking Dead, Snoop Dog and others. Ac.Amir's blog features a greater selection of separate downloads for Max Payne, Agent 47, Battlefield 3 soldiers and even Christiano Ronaldo (complete with scary staring eyes).
To install the models, use Spark IV to browse your GTA file directory. Import the new animation files into GTAIV -> PC -> Anim -> anim.img and import the new model files into GTAIV -> PC -> models -> cdimages -> playerped.rpf.
The first time I roamed Liberty City as the Hulk I got hit by a car, punched by the driver, and then arrested by a chubby bald policeman. Embarrassing. For a more authentic Hulk experience, use the Simple Trainer highlighted above to activate god mode and consider employing something like the Mega Super Jump script.
As with the Hulk in the example above, you can combine a series of mods to turn Nico into the Man of Steel. The Superman mod will let take off and blast through the air, and this chin-tastic Superman model will provide the visual transformation you need. You can find full installation instructions in our previous post about becoming Superman in GTA 4.
And that's all for now. Share your favorite GTA 4 mods in the comments. Do you have any stupendously beautiful screenshots of a modded-up GTA 4? Share them on in the screenshots thread on our forums.