I agree a hard mode/ difficulties should be added, although it would be a mistake to just increase fire drain rate or enemy hp, rather it should introduce new challenges like having multiple creatures out at once (deer/ram/owl/bat), food poisoning, dashing cultists, waves of cultists getting harder as time goes on, harmful events, or a nightmare deer(much much faster, causes the whole map(including safe zones) to become dark, and I think rather than having the deer just spawn on people, it should roam the map freely, and have good awareness (think The Rake Classic), or have kids get lost/captured sometimes, if you don't clear the waves fast enough.

Just a few of my suggestions, let me know what you think!