You have to organize a game with another person, either someone you trust enough to share your IP with, or someone who will share theirs with you. Alternatively, if you have multiple computers on the same local network, you can play over LAN with them. In both cases though you need to do manual IP address entry, but local IP address in the case of LAN.
I don't know if it exactly meets the jam requirements either! It follows the letter of the rules and it may or may not follow the spirit of the rules. Either way, I do game jams to learn and improve my skills, and I wanted to make a networked game so I did.