Chiller is most probably the most brutal and definitely the sickest game to ever hit the Nintendo NES. Not surprisingly then, it was never licensed or approved by Nintendo and was only sold by American Game Cartridges, ending up quite the rarity. You can find more about it here, here and here. If you are actually interested in owning this lightgun gore-fest you can of course bid on this Chiller (NES) eBay auction for the NTSC version of the game. The game is new and sealed.
Seller ships to the Americas, Europe, Asia and Australia.