Assassin

You are an assassin, that works for the government.

Buy all gun parts from the traders. Get close to one of them and hold SPACEBAR for a while. You'll see the gun part fill in the bottom menu.
Once you completed your gun, you're ready to shoot the terrorists. If they are within short range press mouse button to shoot.

You'll cross by some civilians. They're not dangerous.

Look for the cops. They don't know you're working undercover.

Keep out of their line of sight or you'll be arrested.