First there was SimCity, then Sims, then a whole bunch of others and suddenly the GOAT appeared. Now we have a fox in the house. Nice I like all the ideas that have been presented so far. How about aging? Animals are not immortal. I got various numbers from google for red fox. Anything from 2 to 5 years in the wild it seems. Ending up killed and all that not-so-fun is the reason for wide variation of course.
For the sake of it let's say that our Fox would live 6 years and die of old age without illnesses. One day is one hour. That would mean that one game would give the player 2 190 hours to live as a fox before the Grim Animal Reaper would come to claim it's soul. That is a lot of hours...
Well, it is an idea not a final mechanic XP