The Aliens vs. Predator 2 Master Server Patch (2.4) has implemented a fix for the mouse problem. It's not necessary to install all files from the patch, only AVP2P5.REZ and steamworks.dll. Commandline option must be edited accordingly: "lithtech.exe ... -rez AVP2P5.REZ" Wiki code: Uncontrollable mouse movement Mouse moves in wavelike pattern when attempting y-axis movement. Install Aliens vs. Predator 2 Master Server Patch (2.4) This is a requested edit. This notice will be removed when resolved.