@gamingonlinux
Thankfully that has only happened to me once (Dragons and Titans). Being late to the whole Steam thing, I started out buying a ton of games, and for a long time I maintained a consistent 50% of my Steam library unplayed.
I also try to play the oldest games first, so I have a few years of backlog. Plus I bought most of the games on sale, so already not the newest when I bought them.
Too bad with Dragons and Titans, of the three MOBAs I have (Dota 2, Awesomenauts and D&T), it was the one I liked the most.