Ubi Soft Entertainment, a Paris-based video game software maker, said it agreed to buy author Tom Clancy's closely held game company, Red Storm Entertainment Inc., for $45 million in cash to boost U.S. sales. Ubi Soft said the acquisition, expected to close by the end of September, will add $20 million in U.S. sales in its fiscal year ending in March and $50 million to $60 million in fiscal 2002. The company raised its growth forecast for sales and operating income to 30% for this year from 25%, it said. The purchase is the latest move by a French game maker to expand in the U.S. through acquisitions. Other French companies that have purchased or gained control of U.S. game makers in recent months include Titus Interactive, Infogrames Entertainment and Vivendi.