I run a CoC game and played in one in the past in which the GM simply vanished. Is there any way I can take that game and start running it again? Because I really liked the concept.

Only if you were already a GM in that game, and the owner has not been about for at least three months and did not have the "sole ownership" flag on.

There is, however, nothing preventing you setting up your own game, with a similar concept.

In reply to bigbadron (msg # 2):

Ah, thank you, I'll definitely try that then.