I'd prefer a survival mode with more people (8 or more) and making the dead survivors transform into the special zombies, some newmaps... a damn new mechanic of gameplay not a worst last episode mode. That's something we can do that with the damn SDK.
The only reason I see for the delay of the release of the SDK is the possibility that people adapt the current campaigns into the new mode/versus instead of doing it Valve... and that sucks.
