I recently started the early planning stages for a new campaign for Left 4 Dead 2. I'm working on it with Kosire and it's set in down town Miami and its surrounding areas. I've decided to use this blog to document its progress, so I aim to be showing the maps in their early stages right through to the final playable versions. For now, here's some initial level plans with concept images and the rough block layout in Hammer.
Very early stuff as you can see! More coming soon.