Loving this game so far. However..
I believe the game would benefit largely with having more threats to the player. Considering you can throw yourself off a cliff and survive (only saying "ouch" and losing 10 calories), you can starve for eternity and you don't need to sleep. Not to mention how you can witness the asteroid colision and live to tell the tale. It would be so cool to have the option of bunkering down to try and survive the apocolypse if you weren't able to stop it.
Some additions such as fall damage, starvation, hydration, stamina, and hostile animals (such as bears, lions, wolves and sharks in the water) would add so much immersion to the game and opportunity to add a medic profession.
Also weather could coincide with the hydration thing pretty well if you could collect water from rain and store in water tanks, not to mention clouds and rain would look awesome in this game.
Just a suggestion :)