here's a germ of an oddball story idea for Captive prince, spawned by the Wikipedia article about "interregnum." Among all the discussions of tsars and kings and emperors and queens and princes, including historical and fictional, there is a section on chess!
what if it were CHESS that determined the next ruler of each country? citing Wikipedia: "FIDE, the world governing body of international chess competition, has had two Interregnum periods of having no chess champions, both during the 1940s." (the preceding men's champion died of natural causes and the preceding women's champion was killed during World War II.)
so – – of the top of my head, Theomedes won the championships that gave him sovereignty one at a time over Akielos, Delpha, etc (as cited somewhere in the books I think) rather than warfare. And he continued to win whenever challenged. Damen of course trained with the best chess masters in expectation of winning after his father's death in the future. Aleron had likewise gained the Kingship of Vere, and of course Auguste had been winning all the lesser chess titles in expectation of following his father.
meanwhile, Kastor had been learning chess since he was old enough to understand the rules, and his father had abandoned his training after Damen came along. But he continued training in secret. And then one day he challenged Damen but managed to drug him before the match and so Kastor won.
meanwhile part two, in Vere, Aleron died probably by some evil plot and ditto Auguste before he could prove his championship, and then the Regent either faked his own championship or simply decided that that was a stupid way to become king and took over by force…
so eventually Laurent has to beat the Regent in chess publicly before the Regent kills him, and he has to try to beat Damen, possibly in private, because it was something to do with Auguste losing to Damen in a chess match that led to his death... but, twist, Laurent actually wins that private match? I mean, it's Laurent. And chess.
That is all. I doubt I'm going to write that.
Tip: Roger Zelazny wrote a short story, "unicorn variations", about chess where some human had to play chess against the unicorn in charge of the world to save humanity (?), And Zelazny wrote sometime after it won awards that he had scoured the details of chess games from many championships until he found one that had sort of a "tricky" and unexpected move that allowed the underdog to beat the current champion. And he worked that into the story. 
