Wow this is an amazing work! It really does look as if it was torn right off the walls of rapture. Actually, when I was looking for Bioshock posters on google your pic was one of the results and before I clicked the link to enlarge the pic I was pretty sure that this poster was out of the game.
I hope you don't mind, but I linked back to this on my facebook page to advertise my bioshock themed 21st birthday party. If this isn't alright, I will remove it. I gave you full credit, by the way. Awesome work!