Hello!
I'm not sure if you've heard about it before but the Libre Software Meeting are a non-commercial cycle of conferences, round tables and practical workshops based on Libre Software and its uses. It started as a french event and it's trying to become as international as possible as the years pass.
Last year it was in Geneva, Switzerland and this year it is in Brussels, Belgium.
Conferences can be either in French or English.
This year, they added a Video-Game topic that I'm in charge of.
So, If you can be in Brussels on the 6 to 11 of july and have something to talk about (your game project, some technology or framework you're using, your ideas about future of FLOSS videogames, about existing ones, …) do not hesitate to submit a talk here : http://2013.rmll.info/en/cfp.html
Oh, and in the LSM there are also stand for associations or such, it would be nice if there are some stand about FLOSS video games around.