You have to deliver stuff from place to place. The more you deliver the more reward you get but the harder it is to carry.
There are people who try to nick your stuff who you can run away or hide from. Or throw your poo at them.
There are also invisible things called BTs that you have to avoid.
As the game goes on you get all sorts of tools to make travelling easier. You build bridges and roads. Stuff other people make shows up in your game.
The story is about extinction and connection. It's a parable about the internet with a bit of a thing about fatherhood alongside. Being kojima it's mad as ****. Really leans into that eerie Japanese horror vibe whilst also being strangely relaxing.