If it's gonna have a shot online, then it'd have to be p2p, but you'd use light effects. Otherwise you get make an NPC that's like:
NPC Code:
if(playerenters){
toweapons -backpal;
}
if(startswith(#L,cln)){
// change cln to whatever all the levelnames start with
}else{
setbackpal dawn4.png; // Or some other backpal
}
But they should have like "removebackpal" or something like that...