Depending on how your sister implements it, the project could teach basic game theory, recursion, a-b pruning, and other advanced (for high school, and somewhat for early college) topics. Show the teacher some of the classic literature, and how even something as "simple" as the Missionaries and cannibals problem can be mapped into the same problem space.

Perhaps the game is not the way to present it to the teacher, but the way the game is solved.