Proteus has number of negatives compared to Glitch.
It is no where near as nicely done as Glitch was. And it's not free, but then that was one of the downfalls of Glitch, in the end.
It is not in a social environment like Glitch was; is stand alone from everything I can see.
If you're looking for a game you can play by your lonesome that seems to have won some awards then ten bucks doesn't sound like a lot of money to shell out.
Except that, for me, it's being on "Steam" is a negative.
And lastly, take a look at the system requirements; you dang near need a game machine to play it.
i think you just get to walk around and explore... the world is procedurally generated as you play, so random and different every time.
no goals, no enemies.. i kind of like that kind of pleasant pointlessness.