The very first, as installed from the retail disc, unpatched version is also still played online:
Live Call of Duty 1.1 Server List (usually these servers don't require a valid cd-key to play)
Version 1.5 can also be downgraded to 1.1 following this tutorial: Call of Duty 1.5 to 1.1
seta com_introplayed "0"
seta com_introplayed "1"
Takes the Nazi dialogue from the German release of the game and patches it over the other localizations' German dialogue. This fixes both some broken phrases and syncing/cutoffs of the dialogue.
seta r_mode -1
seta cg_fov "XX"
Use CoDUOMP Launcher.
Use the command line argument +set com_maxfps X or console command /com_maxfps X, where X is your desired frame rate cap.
+set com_maxfps X
Open the cfg file and change the seta cg_nopredict "1" to seta cg_nopredict "0", or type in the command in the console cg_nopredict "1".
seta cg_nopredict "1"
seta cg_nopredict "0"
A mod which adds new sounds, textures and more.