Any free/cheap PC games worth getting?

[Luke_Bowman]

So I've built my 13 year old nephew a gaming PC for his christmas present and added an SSD and MS Office out of my own pocket as, although we're not close, I love the thought of him getting into what has been an 8+ year hobby of my own now. I don't really want to spend much more on this as I always wait for offers even for myself. I've picked up Lego: The Hobbit and Subnautica already.

Are there any free/cheap PC games on at the moment which I can stick on his machine? Preferably something suitable for a 13 year old (Minecraft etc).

 

[Luke_Bowman]

Thanks for the suggestions guys! I've been keeping an eye out on Humble Bundle and Fanatical etc for anything worth getting but I'm not sure where to draw the line for a 13 year old. I'd love to buy him The Witcher 3 but maybe in a year or two.