Note: This procedure involves editing a game file; create a backup copy of the "ai" folder in the "common" directory. Open the "ai" folder. Delete the "default.qvm" and "squaddefault.qvm" files. Copy and paste the "settings.qvm" files twice. Rename the copies to "squaddefault.qvm" and "default.qvm". During game play all enemies except for tanks and helicopters will ignore you.