Blood Type:
Depending on the specific blood type you choose to play, that factor itself determines the type and difficulty of vampires you're most likely to run in to. Since there are four special blood types, there are also 4 very different vampires.

Vampire Mode:
This code allows you to use and play Keith as a Vampire in one of the final areas of the game. You are only armed with powered up stun gloves. You do have various low/high/jab punches however.

Hidden Pictures:
When you see an unused save computer, you will be able to see Yuka Kobayashi, whom the character Misato, is based on. However, the first save computer does not have any pictures. From the second save point, right under the dance stage after you kill the Mosquito man, you can see the new bonus pictures. There are 2 new pics at each save point from here on.

Better ending:
If you let Geils kill you, the ending is much better than if you kill him.

Special mode:
By finishing the game in under 7 hours, it allows you to play in a Special Mode, with many more options and cheats.