I was down with a very bad cold/fly when I bought Deus Ex: HR close to a year or so ago on a Steam Sale. I got all the way to halfway through Hong Kong or whatever the city was where I had to sneak into the building... and I just couldn't do it. I kept failing over and over whatever way I tried. Probably because my brain wasn't working fully, but I gave up on it. Haven't picked it up since, which is a bit of a shame.
Put my back out a month or so ago, played State of Decay for days on end... didn't affect my playing though.