Do you want to enjoy Left 4 Dead 2 with your friends, but don’t have an internet connection? No problem! You can play the game in LAN mode without an internet connection. Here’s how:
First, make sure that all the computers you want to play with are on the same network. Then, open Left 4 Dead 2 and go to the "Options" menu. In the "Game settings" section, enable the "Enable Developer Console" option.
Now, open the Developer Console by pressing the "~" key. Type "sv_lan 1" into the console and press Enter. This will enable LAN mode.
Finally, start a game by typing "map [map name]" into the console. For example, to play on the "No Mercy" map, type "map l4d_hospital01_05".
Have fun!