The following CONSOLE VARIABLES are made available (replace the # sign with a number), 
in-game help is available by typing the "LISTVAR" command at the console:

"MOTIONTRACKERVOLUME" - this is set at its maximum of 1.0 by default, the volume 
                        of the tracker can be reduced by changing this number 
                        (e.g. to 0.75 or0.5).

"CROUCHMODE" - This new console command allows players to change the Aliens crouch/
               crawl to a toggle on/off key by typing "CROUCHMODE 1" at the console.
               "CROUCHMODE 0" changes back to the default setting.