Enter Panzer as a profile name.
Silent Sniper Bullets:
Enter Stealth as a profile name.
Enter Ratbomb as a profile name. Now go shoot some rats. Blammo!
Beat the game under any difficulty setting.
During gameplay, hold R2 until you see a camera icon appear in the upper right corner. Then press up or down to zoom the view in and out.
Thanks to Revolution readers Will-loves-Allison, andder and TANX!