The only first person puzzler that can stand up to the Portal series and even beat it. This is a must play for any puzzle fan and will always be one of my favorites. One of the few games that truly makes you think whether it's the philosophies it presents or the tough as nails puzzles. Only complaint is completion. The collectables in this game are a bit excessive. While some of the stars make you think outside of the box others are way too difficult and if you've tried to earn them on your own you'll know what I mean. And getting all the text files is just an extremely long chore. If you play this just focus on finishing it. The DLC is great too btw.