As one who owns a computer and knows what Steam is, I have a massive collection of steam games that are in some state between never installed and probably mostly finished with a few that I would even consider actually done. Typically, I just migrate from one game to the next, rarely actually putting in enough time to really finish games. The long and short of it is that I just jump from game to game or play a lot of multiplayer games so I usually just jump to the next game when its cheap or brighter and shinier.
How do you finish games? Do you march down the checklist and no game is finished until you have seen and done everything? Is a quick trip through the story enough? What makes you lose interest or just plain give up? Also, is the completionist mentality (that I once was apart of) a dying minority or still going strong in its own niche?