|If you pay your ISP for a static IP then that would be your external (WAN) address. |
If you have a SOHO router at home, your internal (LAN) address will likely be a class C private (nonroutable) addressing scheme as provided by your router's DHCP server.
Whether static or dynamic, IP addresses provided by your ISP will be your external (WAN) address.
As I said above, if you only connect to game servers from your home then you do not need a static external IP address. If however you want to run a game server from your home, then it would need to be static. However, running a game server from home would be a complete waste of time. All it would take is someone on your home network to start downloading a big file, stream a video or do some other bandwwidth intensive thing and clients connected to your game server would bog down.
If you're really interested in running a game server, there are many hosting companies out there that will provide everything you need including space on a physical server.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.