Hundreds of users have reported problems accessing Call of Duty and Blizzard Battle.net on Friday.
The first-person shooter game that is available for gaming consoles and PCs can be played with others online.
On Friday, hundreds of players reported having issues connecting to the service via web monitoring site DownDetector.
Video game company Blizzard’s Battle.net, an Internet-based online game and social networking service is also facing problems.
It allows users to play games including World of Warcraft, Starcraft, Diablo, Hearthstone and Heroes of the Storm.
League of Legends, a multiplayer online battle arena video game for Windows and OS X, is also reported to be suffering problems.
Blizzard has been contacted for comment.