The House of the Dead

Secret Options from Isaac Lim & Nick Nord
On the main options screen where you can choose the modes like Saturn mode, Arcade mode, Boss mode etc, press the buttons 'L,R,R,L,L,R' While still holding those buttons, choose arcade mode. (you don't have to do it while hi-lighting arcade mode) Hold it until a menu appears. It works for all versions of the game.

Score Display from Pruthisith & Nick Nord
A bit pointless but if you want to see the good ending you'll need this. When playing pause the game and hold down L and R and press X three times. Please note you'll need 62,000 or higher to get the good ending.

Unlimited Ammo from Pruthisith & Nick Nord
To get this pause the game during play and hold down L and R and press Y three times.

Secret Characters from Pruthisith & Nick Nord
At the character selection screen in Saturn mode hold L and R, then press up, down, X,Y,Z and you'll be able to pick Sophie and one of the researchers.