Can't figure out how to get the online working, I know I have to do some port forwarding and open 11100 but when I try it doesn't work. Anyone know how to get this working so I can play with friends?

I've never had success in port forwarding due to how my router configuration is and whatnot. Instead, I just used Hamachi. Going the Hamachi way you don't need to port fwd anything and you should be able host a game with ease. Just make sure you're buddies join your Hamachi network. That is how I hosted coop games for Risk of Rain.

This is the community made steam guide I used to walk you through the process if you don't know a thing about Hamachi already: http://steamcommunity.com/sharedfiles/filedetails/?id=194047418

Man I wish PC games would just work without having to use hamachi all the time for smaller games without huge net code budgets.