We had decided that myself, our level designer Robin and his brother Tristan (who had very kindly volunteered to help out and donated his PC) would go down at the start of the festival and flyer, while Ian (who was away working) would join us the day before the event.
We spoke to a lot of people while flyering and gave out 2000 of the little buggers -- I was disappointed that this didn't particularly seem to affect either our web traffic or the number of people who eventually turned up to the event. I'm still pleased we did this, because now I know for a fact that flyering even inside a very open festival environment like that does little. I would still keep some printed material available for people to take away, but not push this actively next time.
This would have also meant that we could have dramatically reduced the cost by having the three of us there for less time.
Both Robin (who actually injured his foot while walking around at one point -- never underestimate the unexpected) and Tristan did an amazing job of helping out. On the plus side, people did notice what we were doing and it gave us more of a presence at the festival if nothing else.
Having this number of people was vital when it came to setting up and running the event, so if anything, I would recommend you have at least one person per three stations. These people can be festival stewards / volunteers (as long as you can quickly brief them beforehand) if such people are available.
It's important to take into account the cost of having people away from the office, especially in a small company: certain things will have to be delayed.
On the day itself, we managed to get in successfully, with only a little bit of cable juggling.
People responded very well to a tutorial video we'd made that was playing as they came in. Having a short video which explains gameplay is a really, really useful early marketing tool and can function pretty well in this context.
The festival game mode we created was a success: people got it, understood it quickly and found it fun and challenging. It's such a good game mode that we're actually using it as one of the main components of multiplayer. The benefits of trying to sell your game quickly in a pressurized environment really rub off and have a net positive impact on design.
We did learn quite a lot about the game from observing people playing -- there are still some difficulties with the interface that we're getting over. We found that people were either hooked immediately or very turned off by the game; it's pretty divisive. We'd anticipated this, but it really brought home to me how much we'll need to target our advertising when we get towards launch: we could easily waste money on useless ad impressions unless we hit our target square on.
A lot of people liked it; people walking in literally off the street, sitting down and playing our game like it was an arcade machine was an amazing experience and very motivating. Some people got addicted and stayed for hours, chatting with us and even teaching new people how to play.
I think this whole atmosphere was a particular boost for Ian, who often has to put up with my endless whinging about accessibility and instant impact: he's managed to create a game which a lot of people are going to love and we know this now for a fact!