Young Black Jack

Both feature a doctor who operates on the other side of the law. I honestly wouldn't be surprised if Black Jack and Dr. Tenma were classmates. 

Both are prequels to old school series which also have the same creator. One is light-hearted and fun while the other is dark and gritty. 

Main protagonist is different from most people and have something unique about them. Black Jack is studying a whole lot about medicine and is a natural, Inuyashiki on the other hand received some powers and wants to help others. Both anime have some action, bit of killing and will to help others. 

- Both based on historical events in time. - Both give off the same sort of vibe. - Both are episodic. - Both have some Americans in Japan due to war. - Both have a theme of illegality. 

Both are episodic thrillers with a well researched take on their specific historical time periods. They also both deal with casualties of war, with Joker Game focusing on WW2 and Young Black Jack having an arc on the Vietnam War. The concept of who is right and who is wrong is often in the grey area in these two series. So if you enjoyed these aspects of Joker Game, you should check out YBJ, though a prequel series to a long franchise, you can still start from here without prior knowledge of the Black Jack franchise or character. 

Both series feature alternate stories to the tormented character Hyakkimaru. Despite the differences in age and animation I believe the tragic content manages to be portrayed effectively.  

Minus actual concept (Akagi revolving around gaming and YBJ around medical surgeries), both series give similar feelings...they did to me. I think anyone who has ever seen Akagi will immediately identify him with Jack, or vise versa. And the atmosphere in the two series is practically identical.