Each episode usually deals with a certain spy faced with a unique set of challenges in his mission. Joker Game basically involves a group of spies in the secretive D-Agency of the IJA engaging in espionage and intelligence gathering in various locations around the world.
Looking at the synopsis, the show would have been of interest to fans of spy movies and shows.
Joker Game seems to have failed to live up to its full potential, but at the very least, it was still worth watching.