Check with the manufacturer of the Router for details on port forwarding and with the Game manufacturer as to what ports the Game requires to be open.
If all else fails, RTFM.
P
hey im attempting to play online games between my Imac G3 and my friends g4. We have tried age of empires II, DooM, and Quake III, none working. I have an asante fr1000 router and he has an xsense router. I've tried port forwarding, but may have been doing it wrong since it seems no one can give me clear directions on how to do it. can someone please helP?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic