Grand Theft Auto III - The Definitive Edition

This will come naturally as you progress through the game. Pretty much every action you do such as completing missions, collecting hidden packages, rampage and unique stunts, side missions like Paramedic gets you money. You can even have this before you leave Portland if you have done all the side quests required for 100% on that island. And completing all the unique stunts or collecting the hidden packages will both award you $1,000,000 for getting them all.