You'll constantly have police breathing down your neck. If that wasn't bad enough, rival gang members are always out to kill you and take what's yours. Start a gang and fight for respect and territory. Or go at it alone and see how long you can survive.
Once you work your way up to high ranks in a city, you'll be able to challenge the ruler of that city and take their throne. If you win, you'll be invited, by bigger criminal organizations, to travel to new locations and attempt to take over that city as well. Take over each city until you rule the criminal world.
This isn't one of those Mafia/War games. You'll need real street smarts and ability to strategize and connive if you want to survive. Trust no one. Just when you think you have a friend in the world, he'll stab you in the back. It's every man for himself. How long can you survive?