It was the UK Games Expo in 2009 and I offered my services for the Friday RPG sessions as a GM to help fill a table and demo my SKETCH game. I designed a dungeon, advertised it and got some interest. I was allocated six places and I filled them all.
I got there in plenty of time on the Friday, set up, and watched the eight or nine other tables around me fill up. I sat there eagerly waiting.
And nobody came.
While the other gamers roared and laughed and rolled their dice I sat there with a vast empty table, the seats all pushed under, the spaces filled with character sheets and notes. The dice were piled in the centre of the table in a neat pyramid and didn't move for the two hours I waited. I sat and wrote notes and tried to look busy, but considering the trade halls were not open until the next day I couldn't even take a wander around the show.
As I was also covering the show for two online magazines I was given a free pass for the weekend so it wasn't a total loss. But I never found out why they never came - as far as I can tell they all signed up independantly and they never knew each other, so it's not like they all bailed for the same reason.
The thing I remember the most is the DM running a game at the next table looking over at me with a pained expression, like she really felt my pain, and then she leaned over and whispered, 'Are you sure you got your times right?'
Yes. Yes, I did.