I'm not about to implement Hamachi in JJ2 just so that a few more people can host levels. I am, however, still trying to get UPnP to work which should help a lot with hosting, but I'm currently distracted with other large and somewhat unnecessary projects... Maybe I should've let Cpp handle UPnP when he was somewhat willing.

Then again, it might not be worth halting other projects just to get UPnP working through JJ2+. This looks like a good time to test something. I need people who can't host (those who want an easier way to forward JJ2 ports may be interested as well) to download this file: JJ2-UPnP-BatchFiles.zip. Extract all the files to the same folder and then run Add10052TCPandUDP.bat to forward ports. Make sure to run Remove10052TCPandUDP.bat when you're done. You may want to see what ports are already forwarded with ListForwardedPorts.bat.