How can I best defeat my gaming backlog?

My total steamlibrary sits at around 900 Games and has a worth of about 10.000$, but I haven't even touched over 500 of them!
As time goes by I seem to have less and less motivation to actually play the games, but the urge to collect them is stronger then ever: buy all the bundles, get all the deals, make the library grow and feel good about it.
Even when I try to sit down and finish a game I just stop after half an hour and do something else, my attention span seems to be at an all time low and I have no idea how to boost it.

So the question is: How can I defeat the evil backlog and stop myself from getting distracted even while playing games I want to finish?
Also here is a small incentive for your help. :3

Edit: Better post this here for everyone to see.
Hooray, I just finished a game!
I came to terms with the fact that I can probably never beat all of my games. With that realization came the acceptance of playing on easy and cheating the everloving crap out of a story-focused game if I get stuck for a prolonged amount of time. Obviously that does not count for games like Super Meat Boy or Dark Souls, where the tough journey is the goal in itself, but I'll see. I will try out strategy games and rougelikes, but most of them are to time consuming or based around endless repetition, eating time like no ones business.
I will reduce the amount of bundles I buy, already skipped some this month, and will resist the urge to buy newer games on sale unless it's the goty at 75% or something like that. Achievmenthunting will also have to take a backseat, I will prioritize beating the game at all above all else and won't come back to it unless I have a lot of fun doing the achievments.
Last but not least I will try to check the games at howlongtobeat.com to get a grasp of the time I would have to spend on them.

Thanks to everyone for the suggestions, I will continue to collect games without feeling bad about it and I hope to tame the backlog some day and force it upon my enemies.