Nintendo Co Ltd's hotly-awaited mobile title Mario Kart Tour launched on Wednesday with many users complaining server overload meant they were unable to play the game - seen as a major test of the Kyoto-based company's mobile ambitions.

"The servers are experiencing heavy traffic. Your log-in request will be processed in the order it was received," reads a message that appears when the game is launched.

Nintendo did not respond to a request for immediate comment.