Sorry, I could only find the link in Italian:
Volo cancellato, 170 persone bloccate a Kos «Senza assistenza: č un'odissea» - Corriere.it
It seems that Ryan Air has cancelled Thursday's flight without informing the passengers. They had already checked in and had been queuing for almost 4 hours.
The worst is that there was no assistance both from the company and from the local airport staff.
It seems that the official reason for cancelling is bad visibility, but passengers and local witnesses say visibility was ok. More likely the a/c had some technical issues which could not be fixed.