MTV decided to find out. Using the Wii's Nintendo Channel - which tracks the playing habits of 1.6 million Americans - they've yanked out some data on what games you're playing, and for how long.
The most-played game on the console (at least among those 1.6 million)? That one's easy. It's Super Smash Bros. Brawl, the average player (just the average player!) putting in 64 hours and 51 minutes. Or, in layman's terms, more than a lot of people put into Oblivion.
Second is Guitar Hero III, at an average of 58 hours & 41 minutes, while Twilight Princess came in third at 46 hours, 29 minutes. Perhaps the most interesting (and sad) of the lot, though, is #13 on the list: Okami. It says the average time spent playing Okami has been a relatively paltry 19 hours & 43 minutes, meaning that's a hell of a lot of people who don't even get halfway through the game before calling it quits.