Imagine... Batman chasing Jack the Ripper around Victorian (looking) London. Have you imagined it? Now imagine a game about it. Stop!
You don't need to imagine that, you can see it in the video below.
Siliconera reports that, "Gotham by Gaslight was developed as a pitch for PS3 and Xbox 360 between 2009 and 2010. The game was designed with a foggy world for Batman to explore and he would have the ability to see in the dark. Day 1 Studios tried to work with THQ to publish the game, but after an unsuccessful pitch Gotham by Gaslight was canned."