Restoration of the original version per request.
We're only fixing what's necessary, such as models, nav, sounds, string tables, textures.
This version might still have the crashing at the finale which is random.
Last official update by the original author/creator remains March 9, 2012

June 2011, from the one of the original authors, from the alternative "Game Maps" community:

Hi.

Finding information and help for L4D authoring tools is close to impossible, where most of your questions are never answered and you spend most of your time discussing off topic on L4D authoring forums and mailing lists. Now I can design and map pretty good for my own standards, but I'm not a programmer and not an investigator. if one needs to be those in order to make maps for L4D then I guess I'll have to call it quits. :)

If you know how to solve the problems you see in the campaign then by all means, contact me and I'll give you the VMFs and assets and you're more than welcome to finish/fix Dead Echo.

val