Any nice exploration game?

I read good things about The Solus Project.
Personally, I loved Kairo.

The Stanley Parable

The free demo is available for you

And Astroneer is coming to Steam soon. I'm really looking forward to that one.

Have you played A Story About My Uncle yet?
Not necessarily exploration, but a really nice environment :)

Nice exploration game??? If you can hold a little longer i will recommend No Man's Sky, looks amazing :D

Pixeljunk: Eden is very artsy, and basically only about exploring vast maps to find that one spot you need to go.
Hydrophobia: Prophecy was a very pretty game, with a pretty unique atmosphere, but there ARE action elements to it, so it's more than "Just" exploration.

The Witness
Firewatch
P·O·L·L·E·N

(i haven't played any of them but they are deeply interesting)

And I agree with many other recommendations here too :)

Gone Home
Dear Esther

o/

The Solus Project

Dark Souls

Infra...

You can actually explore in most games; especially sandbox games & open world rpg games.

The Begginers Guide, Dr. Langeskov, The Tiger, and The Terribly Cursed Emerald: A Whirlwind Heist, Gone Home, Dear Esther y bueno, el clásico The Stanley Parable.