Pretty big..

Is this the new gender-neutral internet contest?

It's huge.

About 85% of the games I OWN is backlog, not even kidding. (and I got a ton)

0 - I don't have a backlog... I just play loads of games all the time.

250+ on gog alone. My biggest problem is I always go to my MP games first (red orchestra 2, battlefield 3, Chivalry). I feel slightly relieved now that i know i'm not alone when it comes to being a digital hoarder. At least it's much more sanitary then being a physical hoarder! And nobody at home has to know!

I counted more than 100 once and then gave up counting. I have a lot of games that are interesting, and so long as I don't lose the download links I can pick them up and play whenever.

I do try to mostly buy here on GOG, to avoid picking up duplicates. :)

I recently decided that I'm not going to waste time on games that I can't get into, ones that drag, or ones where its hard to get into due to age. I just took the 3 Legacy of Kain games, Two Worlds II and Jade Empire off my backlog because I couldn't get into Soul Reaver despite the amazing writing, Two Worlds II has a god awful control scheme with M+K AND a controller, and Jade Empire dragged on way too much for the 7 hours I put into it.

RIght now my backlog is looking like:
Clive Barker's Undying
Beyond Good and Evil
Borderlands 2
Darksiders II
Don't Starve (it was a gift so I gotta at least try it out despite not liking this type of game too much)
Sleeping Dogs
Unepic
Ys: The Oath in Felghana

When the Steam Summer Sale starts I'm gonna add:
Ys 1 + 2
Clive Barker's Jericho
Call of Juarez Gunslinger
Analogue: A Hate Story

Somewhere way beyond a hundred games. Making a list would be pointless, really.

I don't call it a backlog. I call it my personal gaming library. Counting all the games (both physical and digital for various platforms), I don't know, could it be even over 1000 games already?

I pick something from the library which sounds nice at the moment, or pick some older one I meant to finish. Now I continued with Baldur's Gate a bit, also trying out The Elder Scrolls: Arena.

I hardly ever start playing a game right after I've bought it, besides maybe just trying it out. I first add it to my library and play it later, maybe.

Its keep growing... Something like a good half-hundred games I think. I've decided recently that I'll simply give up on finishing up some games I don't like and become more picky with my purchases.

My personal digital gaming library: 56 games on GOG, 13 on Dotemu, 4 on Origin. Hm, but physical , maybe 50. This is all PC.

Just 9. Some of them because I can't download them right now, some because my PC can't run them.

Im sure I posted this in another of these topics a few days ago.

Answer: Too long

My backlog is huge because lately my brother has been buying a ton of classic games. Off the top of my head:
Silent Hill 1, 2, 3
Final Fantasy VI
Metal Gear Solid 1, 2, 3
Portal 2
Final Fantasy XIII
Deus Ex: Human Revolution
Ultima 1-7, and Underworld 1 + 2
Elder Scrolls 1 and 2 (waiting for my Mac to ship, then I'll play 'em)
Borderlands 2

Big enough to make me depressed about gaming.

Seriously, I suck at enjoying games these days. Because I tend to start playing games I feel I have a duty to play rather than those I know I'll outright enjoy to play.

Backlog is around 300 games across all systems.

Yeah, I used to do that. And then I discovered ebooks and digital download, and now I just do what I want to when I want to (at least, with my leisure).

I just tell myself "Entertainment doesn't need to be efficient. It just needs to be fun." :D