Hard Boiled Difficulty
If you complete the game on casual mode you will unlock Hard Boiled difficulty.
Extra Ammo
If you run out ammunition but have enough Tequila Bomb for "Precision Aim", use it than aim at someone and shoot. This will create 20 to 30 more rounds for the handgun.
Secret Theater
On the first level, after the second checkpoint when you are walking in the door take a right. You will see a damaged door. Shoot it and walk through. You will end up at a secret theater that shows two previews of games, The Wheelman and Blacksite Area 51. There is also a golden pistol, a paper crane, and a shotgun.
Star Citizen is an upcoming space trading and combat simulator video game for Microsoft Windows. Star Citizen will consist of two main components: first person space combat and trading in a massively multiplayer persistent universe and customizable private servers (known as Star Citizen), and a branching single-player game (known as Squadron 42). The game will also feature VR support.
