DEEP in the wine cellar of the Hotel de Paris in Monte Carlo one evening last month, two dozen of Europe's top video game publishers, along with some American rivals, gathered to toast the Xbox, the newest machine that will run their games. Surrounded by Napoleonic vintages, they dined at the invitation of the game's creator, the Microsoft Corporation, which stands little chance of succeeding in the $20 billion market without their games to propel sales.

One American, Sherry McKenna, who had migrated from the film business to Oddworld Inhabitants, a small development studio in California, typified what they had at stake. Oddworld had scrapped plans to make its next game for Sony's PlayStation2 in favor of the Xbox, tying its future to Microsoft's success in video games. She has doubts, though, about Microsoft's marketing approach.

The Xbox, which goes on sale in North America on Nov. 15, backed by a $500 million marketing budget, is Microsoft's first console and its most ambitious effort yet to conquer the living room in the same way it did the office. Packing the power of a high-end personal computer, the Xbox will challenge both PlayStation2 and Nintendo's coming GameCube with a top-notch graphics chip and a high-speed Internet port. Microsoft is willing to lose as much as $100 on each $300 box to lay a foundation for other consumer devices and to head off the advances of Sony, which has a head start of 20 million systems worldwide, analysts say.

It is anything but a sure thing. Even as Microsoft appears close to settling the government antitrust case that has troubled it for years, its core businesses are shrinking. The days of booming PC sales have ended, and Internet-based software is reducing the importance of Microsoft's operating system. Now a $25.3 billion business, Microsoft faces a sluggish future without strength in new markets. In tackling the booming video game market with an Internet-ready console, Microsoft is willing to lose billions of dollars in a bet that the Xbox will bring in new revenue and help other efforts like interactive television and online services.