Really, the thing that makes this game is the sound design. While the strategy gameplay is compelling, the harsh bark of the shotgun when it goes off, how the music intensifies for a moment after you get jolted back to life, and the tension and/or relief you feel when you hear the click of the hammer falling on a blank round. The sound is what sells the spooky atmosphere more than anything else.
The gameplay itself is fun, too; best way I can describe it is a memory/strategy game revolving around counting shells in a shotgun, trying to deplete the Dealer's life while preserving your own, and using a series of items to influence the game.
It's cheap, spooky, and compelling. I strongly recommend giving it a shot.