Steam is an application created by the gents who created the game we all love... Half Life!
Within it you can buy games, play multiplayer with friends etc etc.
It also has a "Community" function, in which you create a group and can invite people in. Think of it as a facebook page to like! You can create a community and people can sign up to it! get the 40k crowds who play the games! Tbh, its not a b ad idea! and its free to download!
Don't, after rolling that final 1 too many, flip out, climb up on the table and jump up and down on your opponent's models screaming 'APOCALYPTIC BARRAGE, MOTHERFUCKER!!!'.