Open-source games and a LAN party for charity?

I've been thinking of standing up a LAN party in Brisbane for quite some time. I've always missed getting into a room with my PC and just playing games all weekend with like minded sweat lords who also enjoy having no life. That being said, I think it would have to be a one-day thing as I'm 40 now, married, and like to have a shower every day.

Anyway, I'm on the board of directors for my Rotary Club (Rotary Club Brisbane South East) and we're always looking for ways to raise money to feed the homeless (among many other projects that we run that do a whole range of other things.) I had the idea of running a LAN party to achieve this goal!

I have multiple spaces I can operate out of, from our community hall near the Norman Hotel, to Tattersalls Club on Queen Street Mall and others.

I think it would be simple enough to set up, and I was thinking of using open-source games to make licensing easy enough and give us a huge range of games to play (there are loads!)

Right now it's just an idea and I'd love your input.

Thanks.