Would it be possible to make it so there's no trace of any other player within certain levels? If not I'll probably add this to the suggestion forum. It would be good to be able to do for quest levels and trying to build a storyline. It would even make scripting certain things a bit easier, you wouldn't have to script serverside motion as often.
Sorry that I haven't though in-depth about this subject before posting. I figure noplayerkilling, disablefeatures a few features... but I wouldn't quite understand how I could get a player to work if I disabled the player.