The 1.1 update for DOOM 3 includes a number of improvements and fixes for both single player and multiplayer components. The update also includes a new "Dedicated Server" executable. Please see the "update_readme.txt" file for a complete list of changes.
All users must have this update to play multiplayer on updated servers.
Note on previously saved games - This update will NOT make previous single player saved games useless. When loading a saved game, or continuing from your last auto-save, you will start at the beginning of that same map, with the inventory that you had going into that map, fully intact. Using this update will reset the Nightmare skill setting. If you were playing in Nightmare mode before applying the 1.1 update, you will need to re-enable it by pressing ctrl + alt + ~, and typing 'g_nightmare 1' (no quotes) at the console (for more information about how to enter the console, please see the readme file). Then save the game and reload that new save for Nightmare mode to work properly.