Zedlav

Download the .zip file. Extract it anywhere. Run the .exe and then the game should open a Windows Firewall box. Click 'Allow' so that you can connect to other servers (or host your own). It works by default on LAN (e.g. your home network) assuming your firewall settings are configured correctly. 

If you want to host your server outside of your network, like to friends who are elsewhere: Go to your router's page (usually on 192.168.0.1 or something similar), find the section for 'Port Forwarding' and forward the port 4568 to the computer's local IP address where you will be running the game. Then, people outside your network can connect to your server by using your router's public IP.

PLEASE BE VERY CAREFUL sharing your router's public IP address to people, especially people you don't know/trust. This would be a very easy way for hackers to gain access to all the devices on your network. I have no current plans of continuing to develop this game, this means I also won't be making a dedicated public server or adding any security features.

In other words: Use this game outside your own private network at your own risk!