Video game sales peak between September and Christmas as video games are popular gifts. Publishers release their big budget games during this period to boost awareness and sales. Because of this, the time between Christmas and New Year's Day tends to be a dead zone. Few games come out, and big news stories are rare due to many companies being on holiday.
Releasing a video game during this time often leads to abysmal sales. These games don't benefit from media coverage and can fly completely under the radar. While downloadable games have a better chance of survival, it still makes for a less-than-ideal release date.