The Gizmondo lives on as a decent hand-held device for researching and developing augmented reality.
Here is a fishing game demo that uses a map with less obtrusive marker system. I think it supports up to four players at once.
Good idea to slow the pace of the game to match the technology (e.g. reduce motion blur and make tracking less critical). Not a good idea to cover the (graphically pleasant) map with rather synthetic virtual graphics, thus rendering the original map image redundant. Haptic feedback of a fish biting is provided by the rumble feature of the Gizmondo.