The King of Dragons is an arcade game. The Phoenix version, identified by the date code 910731, is one of its releases.  The gameplay would likely involve side-scrolling, dragons, and fighting.  The date code indicates a specific release time. More details about the publisher and developer are needed for a comprehensive understanding.

The King of Dragons (version, 910731 etc)

The King of Dragons (Japan 910805, B-Board 90629B-3)