The only idea I've gotten so far was:
world
New()
var/savefile/Z=new("Hosting/SaveFiles/HasPlayed.savv")
Z["HasPlayed"]>>HasPlayed
..()
Del()
var/savefile/Z=new("Hosting/SaveFiles/HasPlayed.savv")
Z["HasPlayed"]<<HasPlayed
..()
var/list/HasPlayed = list()
mob/Login()
if(key in HasPlayed)
... // Loading stuff
else
... // Creation & tutorial stuff
HasPlayed += key
Question: Is there a better way to do this?