Quoted from HighProtein:What ballys from 1981 should be remade?
February 1981 - Flash Gordon
April 1981 - Eight Ball Deluxe
June 1981 - Embryon
June 1981 - Fireball II
August 1981 - Fathom
September 1981 - Medusa
October 1981 - Centaur
December 1981 - Elektra
Out of that list, I enjoy playing Fireball II the most. More than Fathom, Medusa and Embryon (the ones I own, in order of my ranking)