I've admitted before that I'm a serial non-finisher of video games. I may have played 25-75% of the way into the latest game, but the odds that I've completed it aren't terribly high. I just get distracted once I feel like I've understood a game and what it has to offer, especially if I hit a level that's not much fun to play. Also, around here, there's always another game to try, and I tend to chase shiny objects such as installation DVDs. I did finish Borderlands, Modern Warfare 2, and Bad Company 2 in the past year or so, but I've played a lot more games than I've finished.
The most epic non-completion of my life has to be Half-Life 2. I locked myself into Damage Labs and played almost non-stop for nearly two days (save for eating and sleeping) following the release of the game. I wasn't far from finished when the back and shoulder pain overwhelmed me, but then I was barely able to work at a computer for days. The long healing process and the association with physical pain (and, dare I say it, the plodding pace of some levels and strange sense of solitude with Mr. Freeman) kept me from completing it.
Among the more shameful non-completions of recent years was the original Modern Warfare, where I stalled out half-way into Act I—and this part is critical—before the AC-130 gunner level. My brother has been telling me forever that I need to reinstall that game and experience that level, and this weekend, I finally took his advice. I was able to dig out my old save game, which I'd archived like some kind of freak, since part of my non-finishing complex involves the belief that I'll come back to it eventually. Soon, I was gunning down bad guys in glorious, grainy, black-and-white thermal vision. Very cool, just as it was billed. I've played the level twice, and I expect I'll come back to it every now and then, whenever I have a free moment and want let off some steam. As to whether I'll finish the rest of the game, I dunno. The graphics are kinda dated, and hey, Mafia II looks interesting.