AHA-Lambda It's tricky without sounding reductionist. The gameplay loop is very simple you hike around isolated wilderness with stacked crates on your back delivering reuired items to what are effectively quarantined communities and outposts. The terrain is uneven with streams, rivers ravines and mountains to navigate and there is an amount of physics applied to the boxes that make it more than just pointing a stick on a control pad.
There are hazards which are both natural like weather and slopes etc, supernatural and just other encampments of raiders dotted around. You gradually upgrade your kit and get tools to help you deal with things.
It is a Kojima game so expect LONG cutscenes at certain points in the game usually at major points or when introducing new aspects to the gameplay.
It has a haunting isolation to it which is difficult to describe and which transcends the seemingly simple gameplay. I'd watch some video previews and maybe spoiler free impressions as it's not easy to know if you'll love it or bounce right off it.