My main game is taking all my time so I will never get to this one, but I had an idea I wanted to play around with.. So the MC is a rich man who develops a rare disease which there are no cures for at the time. He decides to cryogenically freeze himself until there is a cure. During this time he is waiting for a cure the world develops a medicine that stops/reverts the aging process for all humans. Everything is going great until all the male population dies off and no females look older than 18 any longer. Wars are fought to claim surviving men, but eventually, all the men die off, and no babies have been born in almost 100 years. A group of young explorers stumble across the building that was damaged during a war which happens to be where the MC is frozen. They unknowingly get him out of the cryogenically frozen state and are very excited to see him as this is the first man that has been seen on Earth in over 100 years. The girls hide the man and get him medicine to cure his disease. From here I figured the game could go in so many directions, the MC helps repopulate, he is hunted for his seed, or really anything is possible.