In a 2010 Eurogamer interview, the game's director Hidetaka Miyazaki revealed that the game's Black and Blue Phantom multiplayer elements were inspired by his experience of driving on a hillside after some heavy snow:

"The origin of that idea is actually due to a personal experience where a car suddenly stopped on a hillside after some heavy snow and started to slip... The car following me also got stuck, and then the one behind it spontaneously bumped into it and started pushing it up the hill... That's it! That's how everyone can get home! Then it was my turn and everyone started pushing my car up the hill, and I managed to get home safely.

But I couldn't stop the car to say thanks to the people who gave me a shove. I'd have just got stuck again if I'd stopped. On the way back home I wondered whether the last person in the line had made it home, and thought that I would probably never meet the people who had helped me. I thought that maybe if we'd met in another place we'd become friends, or maybe we'd just fight...

You could probably call it a connection of mutual assistance between transient people. Oddly, that incident will probably linger in my heart for a long time. Simply because it's fleeting, I think it stays with you a lot longer... like the cherry blossoms we Japanese love so much."
Contributed by MehDeletingLater