Microsoft marketing chief Chris Di Cesare made a bold prediction this week in Variety: He pegged the opening weekend of "Halo 3", the much anticipated third installment in the biggest video game franchise in Microsoft's stables, at $155 million--$4 million more than the opening weekend of "Spider-Man 3," the biggest movie opening in history.

The estimate is certainly not wishful thinking.

The previous installment, "Halo 2," opened with $125 million in sales, and the fanbase of the "Halo" franchise has certainly increased since then. Of course, since video games cost far more than a movie ticket; $155 million in sales for "Halo" doesn't translate into as many viewers as $151 million for "Spider-Man", but bespeaks a huge market. And at $60 retail per copy, a very dedicated one.

So what has made "Halo" so successful? Doubtless, it's a great game, but there are lots of great games out there that aren't smashing box-office records. There's no doubt that the excellent marketing has had a hand in its popularity--and it's marketing that other brands, especially entertainment brands, should note.

Video game designers know how to engage people better than movie producers. It takes an engaging film to keep people in their seats for two hours, but it takes an altogether different sort of engagement to keep people playing a game for 15 hours, 20 hours, or even longer. It's no coincidence, then, that a major part Microsoft's enormously successful and engaging ad campaign for "Halo" has been created by former video game designers: The ARG architects of 42 Entertainment.

If you don't know what an ARG is, then you don't read this column regularly. Josh Lovinson, the other half of Game Insider, wrote a solid backgrounder last month. If you need a refresher, check it out.

The runaway success that is the "Halo" franchise is a testament to the power of ARGs to mobilize a fanbase. Video games, along with other entertainment products, depend on inviting their viewers or players into a world that is somehow different from our own. ARGs give them another way to experience that world, ideally making them hungry for more.

Two other great examples of ARGs around entertainment properties are NBC's "Heroes 360," which allowed players to participate in a campaign to thwart the ambitions of the series villain, Mr. Linderman, and the "Lost Experience," which invited players to explore the motivations of the enigmatic Dharma Initiative. Now, their respective ARGs  aren't solely responsible for the rabid fandom that now surround those two shows. But it can't be all coincidence, can it?