SAN FRANCISCO (AP) — Federal regulators on Thursday launched a legal attack on Microsoft's proposed $69 billion takeover of video game maker Activision Blizzard by depicting it as an anticompetitive weapon while Microsoft hailed the deal as a way to make popular games such as Call of Duty more widely available at cheaper prices.

Those were the dramatically contrasting pictures drawn by lawyers arguing before U.S. District Judge Jacqueline Scott Corley on the first of five days of scheduled hearings in San Francisco that are likely to make or break what would be the most expensive acquisition i...