A lot of this is probably a function of genre, and the popularity and prevalance of genres has changed substantially over the last 30-odd years.<p>This observation is based on a sample size of n=1=myself, so take it with a grain of salt. But the games I've finished have usually been the ones that had some sort of tangible or intangible progression dynamics built in. In other words, the further I got in the game, the more powerful my character became, and/or the richer the gameplay became. RPGs, adventure games, open-world games in which the player could grow more powerful or collect items, games where you built or developed something, etc.<p>Think back to the original Legend of Zelda. I bet that game had a much higher percentage of finishers than many games of its era had. Some of that had to do with novelty, sure. But a lot had to do with the progression of the character, the acquisition of phat lewtz, and the unlocking of secrets. Endgame Link was a substantially different character from n00b Link, and the progress from A to B was remarkably -- if simply and elegantly -- engrossing.<p>Interestingly enough, you didn't really think of it that way when actually playing the game. You didn't say to yourself, from the outset, "I can't wait to slay the demon and save the princess." Instead, you concentrated on the incremental step ahead of you: finding that next level; upgrading the sword; finding the boomerang, or shield, or wand, or what have you. You were very much in the moment, and not always (if at all) cognizant of the linear movement from beginning to end.<p>Contrast this with an FPS or platform game. Your character isn't remarkably different from beginning to end. The only thing that really changes is your skill level, and/or the items you collect (but which are usually expendable, or lost upon death and respawn). The gameplay is interesting, but it's self-contained in its satisfaction: you can derive the same amount of enjoyment from endlessly replaying a handful of maps in Modern Warfare that you get from actually finishing the story mode. And then there's multiplayer, which in many cases is so much more satisfactory than single-player that many players never even <i>begin</i> the story mode.