Oh man, I have that same problem with unplayed Steam games. What makes it even worse is that I buy a lot of bundles from sites like Humble Bundle, usually just because I want one of the games. So now I have about 800 games and I've probably only played 100 of them. I wish I could give those games away...
I 100% know how that goes.
These days, I just keep the codes and give the games away as needed. It's kinda lame that you can't give them away once you redeem them. Unless I'm missing something?
If you're missing something, I'm missing it too! I've started doing the same thing, just not redeeming the keys until I'm ready to play the game. I wish I'd thought of that before I reached 800 games, though.
Live and learn I guess. lol