Black - BFG M249 SAW in City Streets level

Red and black shells:
When reloading the Remington shotgun, the shells are red. However, sometimes the shells are black, and there are no black shotgun shells in the game.

Unlock Black Ops mode:
Complete the game on the Hard difficulty setting to unlock the Black Ops difficulty setting.

Unlock M16A2:
Complete the game on the Black Ops difficulty setting. You will now have the M16A2 M16 with grenade launcher attachment on all levels.

Unlock Silver weapons:
Complete the game on any difficulty setting to unlock silver weapons for that difficulty and any lower difficulty settings. This does not include the Black Ops difficulty setting. You will always have silver weapons on that difficulty setting.

Aurora stealth plane:
In the first mission, under any difficulty level other than easy, you can destroy Intel as a secondary objective. One of those Intel-containing laptops once destroyed holds information on an 'Experimenting aircraft code named 'Aurora'.' The 'Aurora' is supposedly a real, yet secret, aircraft. Most of the Intel is real or based on real world information.

Defeating enemies:
Use destructive objects to your advantage to shock, hurt or even kill your enemies.

Defeating enemies with body armor and shields:
There is no real secret to use with enemies with full body armor. Head shots will not work, just try to shoot. For enemies with shields, use RPGs or grenades. Or, get behind them and kill them by shooting them in the back.