Game developers may legally pursue distributors of such files under laws prohibiting "devices or services that circumvent technological protection measures." Users downloading packs containing 3dmgame.ini are engaging in software piracy.
Sometimes, a 3dmgame.ini file might conflict with a "Steamworks Fix" (a patch that lets cracked players play online via the Steam client's demo servers). You often have to delete or rename 3dmgame.ini to get the multiplayer fix to work. 3dmgame.ini