Secret City: SEGA DREAMCAST

AEROWINGS
Enable the creat mode:
At the title screen, press the L button and R button at the same time. This should unlock everything!

CRAZY TAXI
Crazy Bike:
At the character secletion screen, hit L, R, L, R, L really fast, then hit A. It has to be done really quick or it won't work.

EXPENDABLE
Invincibility:
Pause your current game and hit: Up, Down, Left, Right, X, Up, Down, Left, Right, Y, then unpause.
Skip a level:
Pause your current game and hit: Y, Y, X, X, L, R, Down, Down, Up, Up, then unpause.

HOUSE OF THE DEAD
Show the score:
At the 'Press Start' title screen hit: Left, Left, Right, Right, Right, Left, Right, Start. Now you can see the score that may give you a different ending.

LEGACY OF KAIN: SOUL REAVER
Full health:
Pause your current game and hold L while you hit: Right, B, Down, Up, Down, Up, then unpause.
All abilities:
Pause your current game and hold L while you hit: Up, Up, Down, Right, Right, Left, B, Right, Left, Down, then unpause.

MARVEL vs CAPCOM 2: A New Age of Heroes
Change Your Character During the Game:
Hold L for the second character and R for the third character at the versus screen. This will allow you to manipulate the order of your characters. For example if you select Cable, Ryu, then Ken, but later in the second stage you want Ryu to appear first.
A Change of Clothing:
Press Y or A to choose a fighter at the character selection screen.
Same Character:
If you earn an experience level of 99 or higher in the Secret Factor section, you are allowed to choose the same character up to three times on one team.

READY 2 RUMBLE
Unlock all of the characters in Arcade mode:
At the name you gym screen enter the code: POD_5!

SEGA RALLY 2
All tracks:
At the Title screen, press Up, Left, Down, Right, B, A, B, Right, Down. You'll hear a sound to confirm entry. This will unlock all of the tracks.
All cars:
At the Title screen, press Up, Down, Up, B, A, Left, B, B, Down. You'll hear a sound to confirm entry. Now all of the cars are playable.
Higher 60per frame rate:
At the Main Menu, press Up, A, Down, Down, Left, Right, B, B, Down. You'll hear a sound to confirm entry.
Alternate car colors:
At the Car Selection screen, highlight a car and press L to change its color.
Control replays:
During a replay, press A, Y, or X to change the view and press B to return to the normal replay angle.

SONIC Adventure
Play as Super Sonic:
Beat the game with every character and the 7th character -"Super Sonic" - will be opened.
Play as Tails:
After he is obtained, use Controller 2 to play as Tails.
Hidden artwork:
Put the game disc in a PC CD-ROM drive to find additional art images from the game

TONY HAWK PRO STAKER
Unlock levels, boards, etc.:
Pause your current game and hold L while you hit B, Right, Up, Down, B, Right, Up, X, Y then unpause. The pause menu should shake if it worked!

VIRTUA FIGHTER 3 Team Battle
Play as Gold Dural:
Press Start + A + Y at the Character select screen in Training Mode.
Play as Silver Dural:
Press Start + A + X at the Character select screen in Training Mode.
Alternate costumes:
Hold Start while selecting a character to see their alternate costume.
Slow-mo replay:
Before the instant replay starts, press B to watch it in slow motion.

WWF ROYAL RUMBLE
Get Vince and Shane McMahon:
First finish the one player game on any difficulty and Vince McMahon should be now selectable. Get Shane by completing a Royal Rumble match, and you don't even have to be the winner.