Play as Goldman
Goldman, the nemesis of the original "House of the Dead," is a playable character in "House of the Dead 2." Play through "House of the Dead 2" in original mode, and you'll be able to play through the game as Goldman.
Blood Mode
Complete "House of the Dead 2" in Survival Mode and you'll unlock this additional gameplay mode.
Additional Difficulty
Each time you complete the game at a certain level, you'll unlock the next highest level of difficulty.
Infinite Continues
The games are difficult and require lots of practice to get through, so increasing the number of "continues" is a boon to the struggling player. Play through both Training Mode and Boss Mode, and you'll unlock the ability to play through with an infinite number of "continues."
Score Display
On the "House of the Dead 2" title screen, type in the following code: "Left, Left, Right, Right, Right, Left, Right, A," and a "0" score will appear at the top of the screen.
Free Play Mode
Complete any chapter with an "A" or "S" rank to play that chapter in Free Play mode.
Zombie Goldman
Unlock Free Play mode, and play through the game getting the lowest possible score on the levels. Miss as many shots as you can and still pass the level, shoot zombies in the chest, not the head, and waste bullets. At the end, when you've completed the levels, you will see Sir Gold himself as a victim of his own designs: a zombie.
Bruno Costume
In "House of the Dead 3," score 70,000 points on the "Sin in Original Mode" level and you'll meet a Maid who hands you the costume.
Emperor Boss Mode
Play Boss Mode, and defeat each of them with a high score. You will unlock the Emperor boss, and a more challenging version of the original Boss Mode.