I been fooling around with different ways to host games in Blockland without the use of port forwarding but today I found a way! This way works in your local area network with uses a program called Hamachi. This program allows users to create and join networks without direct IP connection. I have tested this out with my brother and has worked successfully with almost no lag. Below are the steps you can use to host games without port forwarding.
Hamachi:
https://secure.logmein.com/products/hamachi/list.asp1) Download and install Hamachi for windows or mac or Linux or whatever.
2)Start up Hamachi and wait for it to get ready.
3)On the bottom right hand corner of the screen click on networks and click "create new".
4)Name your connection and give it a memorable password.
5)Ask someone else to start Hamachi and to click networks and click join.
6) make sure the person joining your network types in your network name and password correctly.
7)Now both host and client and on the same network.
8) Host: KEEP HAMACHI OPEN AT ALL TIMES! same goes for client(s)
9)Next the host should open up Blockland with Hamachi still open and click start game.
10) The host has three options internet,LAN,or single player games. Click LAN.
11) The host should start the game and wait for the client to join.
12) The client should also have Blockland open with Hamachi open and click join game. When at the join game screen click "Query LAN".
13) The hosts game should be on the list. Click it join it and have fun!
*This has been tested with my brother in the same household this may or may not work on long distance connections but it most likely will.*
Only downside is that you have to tell everyone you want joining the name of your network and password. *Hamachi network and pass*