Stranglehold

Unlock Hard Boiled Mode

When you have completed the game on 'Casual' mode this new difficulty setting will which will test your skill in the game will become an available option.

Unlock Emergency Ammo

To create an extra 20-30 rounds of ammo when you have run out use Tequila Bomb for Precision Aim and shoot someone. Obviously to do this you need enough Tequila Bomb for the Precision Aim so try to keep enough in reserve for emergency ammo.