One thing to note is that if everyone stops having children, it will create a demographic crisis with a lot of older people / pensioners not able to work and not a lot of working age people to support the aging population. Good for environment ofc but quite bad for the remainder of population.
Surprised nobody mentioned One Hour One Life before.
Basically, it’s a game where you only have 60 minutes to live in an open multiplayer world, starting out as a baby being cared for by your “mother” going to adult, and then dying of old age, possibly leaving everything to your offspring, also actual players.
I found this mechanic to be very unique among other games.