TrapperX asked you something and you ignored his question: your router is a [put your router model here]?
ports in, port out: you have to think you are in the router. ports in: the ports that the router accepts connections (your game ports will be here). ports out: your router sends data to those ports on the destination device.
So, as an example. You have a router and a computer "hidden" behind the router. You want to make a server, a game server, on the hidden computer and you need port forwarding. The game uses ports between p1 (it's a number here) and p2 (another number). Your computer (local) IP is a.b.c.d
On your router you create a new rule:
ports in: p1-p2
(the exact mode of defining that list depends on your router model. What router do you use?)
ports out: p1-p2
destination computer/device: a.b.c.d
(the router will send the data it receives from internet on his p1-p2 ports to the computer's p1-p2 ports. If your computer is not working, no connection is made. Observe: there are the same ports here, p1-p2 on router are the same numbers as p1-p2 on your computer. You can use different combinations, but you have to know what you are doing.)
What router do you use? Maybe it has a link to a manual, to help you with a more specific link; and with a few more specific advices.
