Funny this thread should come up as I recently decided to tackle my unplayed Steam games.
This is how I did it:
I went onto Steamdb to bring up my stats - I think I'd played around 50% of all the games I owned. Disgusted with myself I set up an Excel spreadsheet.
I then imported all the information from my Steamdb profile into this Excel sheet. This included the game titles, time played, and steam review score as a percentage.
Now comes the laborious bit
I straight up deleted all games that I have played and have no intention of playing again in the future.
I also deleted every game with a 50% rating or lower. Since I had over 200 games in the backlog I decided to just be ruthless and assume that most thing with that kind of rating isn't worth my time.
Then I went through each game individually and looked it up on Google to see if it's something I could see myself actually playing for more than 5 minutes - if not: delete it.
This left me with a list of 100 or so games which I want to play, replay, or continue playing. I found it quite difficult to choose what game to play next so I came up with a solution.
I created seperate playlists catagories in Steam. Playlist 1, 2 and 3

I basically have to finish the first playlist before I can move onto playlist 2. No excuses - Just get them played. I also created separate categories for online only games and games which I want to replay at some point.
I also promised myself to be ruthless when playing the games. If I'm not having fun after 30-60 minutes I get rid of it. Mark it as completed on the spreadsheet and move on. There's no point forcing myself through a game which I don't enjoy when I have 100 more sitting there not being played.
So far it seems to working out alright and I don't feel overwhelmed by it. I just play the games and have fun - or not haha.
I actually came across a little gem which I didn't even know I owned. The Detail - check it out!
How sad am I?