Deep within the mountains, this complex has been left to ruin after whatever conflict it was involved in resolved. Bought by Mann Co. for a few hundred dollars, the site is being demolished to make room for a warehouse or two to house all the inventory Mann Co. has accumulated over the years.
A couple of weeks after the workers showed up, the Robots drove in and scared them off. Go and do what it is you folks do and after you're done, you can finish the worker's jobs so we don't have to pay them.
Derelict features the following missions:
Rust Removal (Normal)
Intruder Exclusion (Intermediate)
Torrential Downpour (Advanced1)
Heavy Rain (Advanced2)
Drenching Desolation (Expert, by Nuke)
Cipher Chaos (Survival, by BlazingDiancie)
As of Beta 3, the download is for the map only. The .nav file and missions are available here.