As much as I love my Dreamcast, there are definitely some must plays on the PlayStation 2, especially those that didn't make it past Japan. My favorite PS2 game of all time, having only played it last year, is Tetsujin-28 go. It is based off the popular Manga, and is known as Gigantor in the States. This game was also made by Sandlot who really knew how to make Robot games. They were also responsible for Remote Control Dandy, Remote Control Dandy SF, Robot Alchemic Drive, and the Earth Defence Force series. If you have a Import PS2 I can't recommend this game enough!