Dishonored developer worked on Half-Life 2: Episode Four

We haven't seen a new Half-Life 2 game since Episode Two came out in October 2007. According to the folks at ValveTime and Rock, Paper, Shotgun, that's partly because Valve canned Episode Four, a spooky sequel that would have taken players back to the zombie-infested town of Ravenholm. And you'll never guess who was developing it: Arkane Studios, the same folks who released the excellent Dishonored last year.