100 Challenge Mode:

Beat all nine Outdoor Shooting Range challenges to unlock 100 Challenge Mode.

Night Vision Challenge Mode:

At the mode selection screen hold Trigger and highlight "Training" or "Arcade". Keep Trigger held and press Start 5 times. The sound of a gun will confirm correct code entry. The game will begin at night and require the Night Vision scope.

Professional Night Vision Challenge Mode:

At the mode selection screen, hold trigger and highlight "Training" or "Arcade". Keep Trigger held and press Start 6 times. The sound of a gun will confirm correct code entry. The game will begin at night, with no aiming ring or enemy markers.

Professional Challenge Mode:

At the mode selection screen hold Trigger and highlight "Training" or "Arcade". Keep Trigger held and press Start 4 times. The sound of a gun will confirm correct code entry. The aiming ring and enemy markers will be disabled in this mode.

Extra Options:

Beat the game under any difficulty setting to unlock a real time window and up to 8 health in the options menu. Alternately, accumulate over two hours of game play.

Beat the game more than twice under any difficulty level to unlock infinite credits in the credit section of the options menu and +30 in the time limit section. Alternately, accumulate over three hours of game play to unlock the +30-time limit and over five hours for the infinite credits.

HINTS:

Use The Mouse:

The mouse peripheral for the Sega Dreamcast works in Silent Scope, though there isn't any indication of this on the box. Here is how, just plug in your DC's mouse into any controller port (I have mine in #4) and fire away! Button #1 is fire, button #2 is to add/remove your targeting recital and button #3 or the thumb button is to pause, while the wheel of the mouse is only good for menu scrolling.

Extra Life:

At the start of story mode in the second wave, a pool will appear randomly on one of the smaller buildings. Use your scope to zoom in on the pool and look for a woman in a bikini. If done correctly, instead of your regular scope, it will be a pinkish red heart and you will gain an extra life. This also can be done on the highway level by looking for a pink car.

The Disappearing Act:

Start on other side of a building-when your about to start the arcade game hold Left on the D-pad and if you did it right you'll start on the other side where the bad guys are facing the other way so they can't see you