With the Xbox 360 launch barely behind us, Microsoft says it's going to make a big push in casual mobile games in the first half of 2006, reflecting the interest people have in playing short, simple games on their phones. The company's got a deep understanding of casual games, both through its current efforts with MSN Games and the Xbox Live Arcade, but also going back as far as Windows Solitaire -- probably the most popular and successful casual game. One particular element Microsoft says it will create is the ability to play the same game across the phone, PC, or Xbox. For instance, a user could play chess on their phone against an opponent on a PC. But, of course, users will have to pay to play, like on Xbox Live -- so MS is also deciding how to implement a micropayments system to facilitate the transactions.