Depending on your playstyle, going 100 days with fuling or seeker invasions enabled might be a bit interesting, but I did just that when Mistlands came out (before the balance patch too) and never saw a single seeker invasion in 100 days. Only one gjall invasion. The world I've had since the beginning is past approximately 700 days, so the "challenge" described here sounds just like how I play the game normally solo. So I dunno lol.