A bestselling novel is one thing, but one that has an Internet game designed for its launch is something else again. Nimitz Class, which was published by HarperCollins on June 4, not only enjoys that distinction but, says the publisher, Sink the Nimitz (http://www.nimitzclass.com) is getting thousands of hits per week. Patrick Robinson's techno-thriller -- about a nuclear tragedy with sinister repercussions -- lands at #14 this week; five trips back to press bring the in-print total to just over 100,000 copies. Robinson's extensive tour began on Memorial Day at the Mystic (Conn.) Seaport Museum, moved last week to California and will include four naval bases in the D.C.-Norfolk area. Accompanying the author -- and set to appear with him at the Navy Museum -- is Admiral Sir John Woodward, who worked closely with Robinson on the book's technical details.