EPTThis game: http://freebirdgames.com/to_the_moon/ is just awesome. I played it for ~5h and finished it a couple of hours ago. This last-century graphics game is making you live a story, someone's life story.
I've always loved games who could trip you into their universe, this is definitely one of them. This game made me wet my eyes a little, it's very profound. It gently takes you from sadness to happiness and back.
There's reviews out there to be found should you want, i don't want to write one. I'm just going to say it's a great game (it's actually more of a story, you don't do much as an user) that's got an amazing soundtrack (the music fits just perfect with the game).
If you got 4-5 hours and feel like playing some slow, deep single player game give it a try.
