Vampire Fever
You're Viro, a ninja who stands against evil creatures! Yet you're a complex guy, instead of using conventional weapons, you spread a virus, which only affects demons and undeads. The virus is very contagious among healthy, but it has one weakness: If two sick creature collide, they both heal.
Instructions:
Mouse to aim & shoot. Vampire Fever is a billiard-like physics game, which you control your character "Viro"(instead of the white ball) and try to infect by touching other creatures on the screen.