Under construction for 8 years already and still in Early Access, but if I could, I would nominate Factorio for a Game of the Decade award! It's the gift that keeps on giving... just be prepared to say goodbye to your sleep cycle in return.

Edit: Being under construction for 8 years and 10 months slowly but surely molded Factorio into one of, if not the best factory game out there! Even after final release, it still has so much to offer thanks to the active modding community.

Edit 2: 2.0 and the Space Age DLC are now out and both are wonderful additions. I've nominated Factorio once again for the "Labor of Love" Steam Award, but posting a review for the Space Age DLC didn't count for the badge's "Review a game you've nominated" task for some reason, so I'm updating this review to also recommend the Space Age DLC.