Narbacular Drop (Portal predecessor) documents

The design documents for Narbacular Drop, created by Nuclear Monkey Software, can still be found on the website of DigiPen Institute of Technology.

The original developers showed the Narbacular Drop game to Valve, which offered to let them develop it’s successor Portal at Valve. On this website several different kind of documents about the game can be found (Docs section) as well as the finished game (Downloads section).