I Play Dark Souls 1 in LAN with a friend used a steam emulator. Is any similar mode that can be done with dark souls 3?
It's possible to have direct connection if you are within LAN, but initial matchmaking happens using official game servers in Internet. That means both of you need to purchase the game (if it's not done already).
So for your game it looks like this:
- Go to matchmaking server to find someone to connect. If you are using password matchmaking the game will chose your friend to connect.
- Send packets directly via LAN after they join your game. I'm not sure if it's possible to disable Internet connection at this point.
This video shows how local LAN play looks like - they have no lag at all.