How can I disable the Launcher for Medieval 2: Total War?
Go to the Medieval 2 directory and you should see Launcher.exe and Medieval2.exe. If you open the second the game should start bypassing the launcher -just create a shortcut to desktop of that file for next games-.
If you are running it under Steam, just backup the original Launcher.exe file and rename Medieval2.exe to Launcher.exe, which is the file name Steam will launch.
Source: I did it in the past.