Hydro Thunder

Unlock Bonus track:
Highlight "Back" at the options menu and press
Up, Up, Down, Up, Down, Down, Start.

Full pause screen -
Press X + Y, while paused the gameplay.

Unlock fishing boat:
Unlock all the tracks and highlight Thresher at the Boat Selection
screen. Hold L + R and press View twice.

Faster start
Before the race begins, hold L during the countdown.
when the countdown reaches 3: Release L and hold R
when the countdown reaches 2: Release R and hold L
when the countdown reaches 1: Release L and hold R
Note: This trick works if you have a default controller setting.

House of the Dead 2

Ending Bonus room:
Finish the game in original mode without losing any civilians and
reach minimum 1000,000 points

Unlock "Emperor" option:
Beat all Bosses in Boss mode

Unlock "Fight All" option:
Beat all Bosses in Boss mode

Unlock Goldman costume in the trunk of the car:
Finish the game in original mode.

Change blood color:
Finish the game in Original mode.

Show score:
At the Title screen, press Left, Left, Right, Right, Right, Left,
Right, Start. You'll see a 0 score at the top of the screen to
confirm.

Infinite "one-hit kills" ammo:
Finish training mode and reach 5 red star rank on each stage.

Free play in original mode:
Finish training mode and reach 5 red star rank on each stage.
After, finish boss mode and reach 5 red star rank.
At last, obtain 2 stars in fight all mode.
The "Continue" option will change to "Free Play".

Play as Gary instead of James
In single player mode use a controller in port B.

Training and boss modes:
Finish the game in Original mode.

Napalm Gun:
Get a perfect head shot on the first 3 zombies you see off in the
distance on the first stage. You'll see a gun on the ground if you
did it right.

Bonus room A:
Get to the final boss and have saved all the civilians to access a
secret room with a bunch of good stuff. This room has 3 life ups, 2
diamonds, 2 gold frogs, 2 necklaces, 2 gold coins and a mushroom.

Bonus room B:
Get to the final boss (without saving all the hostages) with over
100,000 points to get an infinite credit powerup and a Rogan costume.

Bonus room C:
Get to the final boss (without saving all the hostages) with 70,000
-100,000 points to get a Dynamite Cop costume.
Submitted by Aston34

Hidden And Dangerous

Unlock all missions and additonal options:
Go to the name entry screen and type the following codes as your name: "RVL"
Keep the "L" highlighted the last letter, so your name will appear as
"RVLL" with the second "L" still flashing. Push Start to delete your
name and press B to go back to the main screen. While playing pause
the gameplay to bring up a cheat menu.

Cheat Codes:
Type "IWILLCHEAT" as a name or at any menu screen during the start of the game
on a Dreamcast Keyboard to enable cheat mode. Then, enter one of the following
codes to activate the indicated cheat effect:

Pause the gameplay and type the following cheat codes on your Dreamcast keyboard.

All items: Type "ALLLOOT"
Big head mode: Type "FUNNYHEAD"
Display player's coordinates: Type "PLAYERCOORDS"
Enemy behind view: Type "ENEMYB"
Frontal view of enemy: Type "ENEMYF"
German version: Type "BLUESTARS"
Invincibility: Type "CANTDIE"
Kill everybody including hostages: Type "KILLTHEMALL"
Mission failure: Type "GAMEFAIL"
Mission skip: Type "MISSIONOVER"
Open all doors in current mission: Type "OPENALLDOOR"
Restore all team members health: Type "GOODHEALTH"
Revive dead teammates: Type "RESURRECTION"
View ending sequence: Type "SHOWTHEEND"
Wireframe graphics: Type "DEBUGDRAWWIRE"