For LAN mode
make a few modifications to the xbox_live.json file in the root of the game directory:
1) You must change at least one value of the “userID” to make it unique from the other computer(s) on the network
– If you don’t, then it WILL not pick up any games
2) Change your gametag to something unique instead of the default
When refreshing the lobby for games or trying to join one will throw up an error message about Xbox live not being available, but just click okay.