Thanks everyone for the feedback, it really means a lot to him. Wasn't trying to start a debate about using AI to learn to code; I just want him excited about building things, and this was one way to do that. He's already looking at some of the suggestions here (hemisphere setting, more species) for the next version.

how would you do it? what would you track?

The amount of years you've been alive divided by the life expectancy of your country.

What do you mean “the life expectancy of your country”? Do you mean “the total (current + remaining) life expectancy for someone of your age in your country”? Or do you mean “the life expectancy at birth in your birth year in your country”? Or something else?