You can't really "beat" The Beginner's Guide, but I last finished The Beginner's Guide, and I'm still reeling from it, honestly -- in the week or so since I played it, it has quickly gone from "I don't know what to do with the emotions I'm feeling but I think it was good" to "....I really wish every creative person could experience this game." As a creator, it hit me hard and resonated with me really deeply.
It is about a friendship with a sort of eccentric creator, explored through that creator's games; a series of short, strange, sometimes powerful experiences that slowly show you a bigger picture. It comes from the guy who wrote the Stanley Parable, if that tells you anything.
If you're not put off by games that are more experience and atmosphere than challenge, I really can't recommend this one enough.
As far as games I've BEATEN, the most recent was Undertale, and if you've been on the internet at all lately you've, uh, probably heard of it. I love every character, and you really feel like your actions matter in a way that none of the big YOUR CHOICES MATTER!!! games have managed to capture. It is tremendously genuine and full of heart. I highly recommend it!