In life, (and in a game) there are ~100 "death timers" such as "thirst", "hunger", "scurvy", "beri-beri", "air", "cold", "injury" constantly running on a player; they drop at different rates, influenced by the environment. The player initially starts with most of them set not to expire for quite a while.
I'd like to see a game where you are presented with choices, and each choice changes the state of a multitude of death timers. Drinking water pushes back the "dying of thirst" timer by a few hours, but going to the water hole marginally increases the "getting eaten by an alligator" background rate.
Players can also get items - so picking up a water filter will permanently improve thirst resistance. Storing 10 gallons of water adds a buffer to he thirst timer. Gaining weight adds a buffer to the starvation timer.
There can be some really speculative timers - boredom, insanity, risk-seeking behavior etc.
Gradually interaction with the environment can be added.
Initially the game just drops them into a blank room somewhere - but if they traveled outdoors, the scales would change, risk factors etc.
Finally, psychological effects come in - boredom, love affairs, fighting, war... politics? cancer timers start running low...
In the end, the game invisibly switches focus from parent to child; this resets the "enemies coming to get you" timer, cancer timers, etc. but temporarily puts you at much more risk of cold, disease, etc.