You need to download the client, either «Nexus 2» or the BlastClient, and extract the files if they are in a .zip archive. You don’t need to install the client – only go to the client folder and open «boot» (or «boot.cfg» if you have file extensions shown). If you want to play on a local server, download a server like 0.5.1 and extract all of the files before starting «LUNI Server.exe». If you want to play on a public server, connect to the web interface, for example http://5.230.147.129/ for Jonny’s server, and register an account.

Now with the boot file you opened, edit AUTHSERVERIP=0:localhost, if you want to connect to a local server or AUTHSERVERIP=0:(public server's IP), for connecting to a public server (for Jonny’s server, AUTHSERVERIP=0:5.230.147.129).

If you have any other questions, please ask 🙂