A game based on a TV series, City Of Vice, by Britain's Channel 4. You play a Bow Street Runner, proto-detectives who became one of England's first professional police forces in the 18th century.
The game is the standard point-and-click type; however, it looks very deep and graphically-interesting, with professionally-acted cut-scenes. You play in your browser; there's nothing to download or install. You don't have to register, but you might want to if you like the game and want to save your place (new episodes will be released in the future).
Warning: As the picture might indicate, the content can be violent, and the language might offend. If you're sensitive to Georgian cursing, that is. Sound you can turn off with a button at the top right.