minstrel

According to a quick search, "69 People found that match Demo in the state of California." I noticed 1 or 2 with the name "Demos", but other than that.....

Perhaps, since sign-up as "Demo" is special functionality anyways, you could ask the user to confirm that they're "Demoing" the account or if their name actually IS "Demo".

Albeit, 69/36.5m < 0.0002% of the population so you could probably get away with letting the user know that they're been automatically "Demo'd" and only fix it if you have to.

"[...]and the game was just a pretext."

Which is exactly the point. Without the pretext of the game, less people would show up for the gathering, resulting in a lower "resulting laughter" quotient.

As one of the "shy ones", I can confirm that having a shared activity encourages me to come to the event, and ensures that noone is "left out" (as their character has something to do, even if they personally have nothing to add socially). An interaction within the confines of the 'game' encourages more voluntary interactions, not to mention giving people a pretext for conversation, etc.