What's a single player PC game you can't get enough of?

Hellblade: Senua's Sacrifice made me gain a deeper understanding of what my BFF went through, almost 13 years ago, when she took her life after battling with psychosis and not able to fight her delusions.

It's an incredibly deep storyline, and they did an amazing job at captivating the essence of how some minds work. I cried when I played, and cried when I completed it, yet they were beautiful tears all the same. Very well made game, and I actually came to this post to give it a mention as well.