The Federal Trade Commission (FTC), which enforces antitrust law, asked a judge to block the transaction earlier this month, arguing that the merger would allow Microsoft's Xbox to get exclusive access to Activision games, leaving Nintendo consoles and Sony's PlayStation out in the cold.

Microsoft has countered that the deal would benefit gamers and gaming companies alike, offering to sign a legally binding consent decree with the FTC to provide "Call of Duty" games to rivals including Sony for a decade.

Microsoft made the argument in a filing aimed at convincing a judge at the FTC to allow the deal to proceed.

The case is a sign of the administration of U.S. President Joe Biden taking a muscular approach to anti-trust enforcement. But antitrust experts say the FTC faces an uphill battle to convince a judge to block the deal, because of the voluntary concessions offered by Microsoft to allay fears it could dominate the gaming market.

(Reporting by Alexandra Alper; editing by Grant McCool)