Off Topic Curious about your listen server
Curious about your listen server
1 
DC, how do you make CS2D's listen server (the 'Create Server' one) work without forwarding a port? This is because I wonder how do your game is the only effective that allows outside player to join my server while the other games don't (it need to be port forwarded). 
You try to connect/ping a server behind a NAT router but the router of the server discards your message or doesn't forward it correctly, because nobody configured a proper forwarding. 
Now a message with your IP and port is sent to the U.S.G.N. masterserver to deal with this problem. The masterserver accepts all messages because it's not behind a NAT router. The masterserver simply forwards this message to the server you are trying to join. The server will accept the message from the masterserver because it communicated with the masterserver before (version check and serverlist entry). The server you are trying to join now sends a packet to you after receiving your IP and port from the masterserver. This leads to a NAT (network address translation) table entry in the server's router which basically means: "I've sent a message to that address! I'm now waiting for an answer and I'll accept all messages from that address and route them to the local address which sent the first message". When you now send another connection/ping request message to the server (this happens automatically after a short delay), the router of the server will handle and forward it correctly because there is a NAT entry for this address combination (consisting of your IP:Port and the local server IP:Port) 
sixpack: said is correct too and also much simpler: sixpack has written 1 
Offline