Get 40 headshoots in a game
Get 6 kills with a single grenade
Kill 5 civilians in a game
Use a civilian as a shield to stop a knife
Shoot down a helicopter by throwing an explosive barrel
Kill the driver of your own boat
Go down to the arcade and hide until time passes without killing anyone
Get 50 stars of story mode
Get 100 stars of story mode
Kill 2 soldiers with a mortar bullet