This really doesn't have to be like an official group or anything, but whynot just have a steam group, so play games together on steam and stuff! And yeah...
I would go the extra mile and say competitive TF2, but A. ywall are probably not that experianced at TF2, B. Probably wouldn't be enough peeps. C. Communication would be a bitch to deal with, sense not everyone would probably have a mic, and D. I wouldn't be able to carry but maybe mentor.