Cheats are now so ingrained in gaming culture that it would almost be frowned upon to not include any in a new release. The seminal “Grand Theft” series lends itself perfectly to a huge variety of cheats because of its first-person, real-life format. Just like in real life, it can flood in Liberty City in “GTA 4,” but only when you know how.
Complete the game
Unlike other cheats that can be used throughout the game, you can only make it flood once you have completed the game, beating Faustin in the last mission.
Head back to the Dukes apartment that your character Niko lived in at the start and put on the first suit you got from the Russian shop.
Hold “L2” and “R2” to start the debug menu, select “Weather Effects” and select “Flash Flood.” When you go outside the flood should be in effect.
You can get rid of the flood by going back to the same apartment and following the same procedure, opting to deselect the flash flood this time.