It's kind of hard to describe Proteus in words to somebody who has not played it.
Sure, you can explain how it takes place on a randomly generated island where you walk around taking in the sights and sounds. You can tell somebody that all the critters and plants and other elements make their own sounds and tones which contribute to the dynamic musical experience of the game. You can even tell them about how different the island is from season to season, and about all of the little things to find and explore.
But no written description will really cover all of the emotions and experiences you get when you play through Proteus. Proteus is about the joy of beauty and discovery, and simply must be played to be fully experienced.
TL;DR If you like chasing frogs and turkeys this game is for you.