I still have several games to complete all of which were bought on day 1.
Fallout NV, I've played this so much, maxed out at least 10 characters, completed all the side quests but have never once actually beaten the main mission.
Darksiders, I normally get about half way through before I distracted by something else.
Mass Effect 1, Bought it a few months ago but I still haven't beaten it, dunno why, just cant get through it.
Torchlight, I've spent many hours with this one but I still cant finish it for some reason.
There are still many, many games on steam that I've bought and haven't even touched yet.