Forget all the hoopla surrounding new video game systems, such as the impossible-to-find Sony PlayStation 3 or the TV-breaking Nintendo Wii - the real gaming story in 2006 was the explosion of so-called "casual games."You know, those try-before-you-buy, downloadable diversions that are a cinch to pick up yet impossible to put down? Just ask your mom what her Zuma high-score is. Most casual games are under a cool $20, or roughly a third of a cost of a next-generation console game.