Strongly depends on what you wana play ... If its CS:GO you only needvalid steam accounts and valid copies of the game, be friends on steam and go MM with freinds. If its 1.6 (or source) you can get it working the usual way (Find Server -> Lan) if it doesn't work you might get it to work with "connect public.ip.of.host" In the console. We used to do the same shit, never even tried to access the routers... My point is from all the MP games I used to played, only minecraft required tinkering with the router, ever ....