Various cheats
     Enter the following cheats during gameplay while the game is
paused:

Infinite Necroplasm and Health:
     Up, Down, Left, Right, Right, Left, Down, Up

Level Select:
     Up, Down, Left, Right, Left, Left, Right, Right

All Weapons: 
     Up, Down, Left, Right, Left, Right, Left, Left

Infinite Ammo: 
     Up, Down, Left, Right, Up, Left, Down, Right

Infinite Necroplasm: 
     Up, Down, Left, Right, Down, Left, Up, Right

No Blood: 
     Up, Down, Left, Right, Up, Up, Up, Up

Unlock Comics: 
     Up, Down, Left, Right, Right, Left, Left, Up

Encyclopedia: 
     Up, Down, Left, Right, Left, Right, Up, Down