Zinderneuf

Hello everyone,
does anyone know what the word "zinderneuf" means, or where it comes from? I've known this word, but not its meaning, for many years from a video game called "Murder on the Zinderneuf".
The game package and ingame design suggest that it must be something like a zeppelin, but I am not sure.
I did not find it in any dictionary or encyclopedia. The only other reference I could find was a certain "Fort Zinderneuf", which possibly exists in reality, maybe somewhere in California, and seems to be featured in an old movie called "Beau Geste".
Thanks for any help!
Chris