BUILDING A state-of-the-art video game collection requires more than deep pockets these days. What you really need is square footage, and lots of it, to store the many accessories that are suddenly must-haves. In a year in which system and game innovation slowed, companies unleashed a flood of gadgets to replace run-of-the-mill controllers. The popular Rock Band and Guitar Hero III may be blasts to play (ask Joel Zumaya), but they require equipment that, in the case of Rock Band, can push the cost of playing the game to over $200. Microsoft, maker of the Xbox 360, is offering a wireless wheel controller ($129.99), roughly the size of a real steering column, for its racing games such as Project Gotham Racing 4 (above). And Nintendo has unleashed the Wii Zapper ($19.99), a wireless gun to be used with several shooting games. ( Bobby Knight, please take note.) More is on the way: In early 2008 Nintendo will unveil Wii Fit (the system hit stores in Japan last week, priced at $75), which comes with a balance board that allows gamers to practice yoga and ski jump in their living rooms. Gamers looking to sweat can also fire up the latest version of Dance Dance Revolution, played by hopping up and down on interactive pads that can be purchased for all systems.