In the olden days of gaming, everything worthwhile came out of Japan, as did all of the console manufacturers. Now, with the game market being much more globalized, American developers have as strong of a foothold in our culture as ever. That is, everywhere but in Japan. There are a lot of facets of our gaming culture that the U.S. holds dear that the Japanese have never even given a second thought to. Here's a list of some of the most surprising (and maybe least surprising, in some cases).
This is probably one that people would be most surprised by, since it's one of the most obsessively played games out there. And if there's one thing they have in the land of the rising sun, it's a slavish obsession with games. Other than Final Fantasy XI and a few others, MMORPG's haven't caught on as much in Japan. The easiest explanation for this is that Japanese gamers don't actually use PC's for gaming that much, so there really isn't much of a market for those games.
This is in the same vein as World of Warcraft. Most indie development happens on PC's, so there isn't as much of a market. In addition, Japanese gaming has historically been a much bigger production than Western gaming. The original Mortal Kombat had 4 people making the whole game, whereas there was a separate artist for each character in Street Fighter 2. Still, it's hard to imagine the gamers of Japan not being able to enjoy a game like Braid. On second thought, given the subject matter, maybe it's best if they never play Braid. Ever.