Usually the best way to go about making edutainment is to make a game where the educational component is as subtle as possible, where knowledge of the topic at hand is necessary to play the game, but players aren't actually direct questions about said topic. Word Rescue is one such game, which is part of the reason why it's as fondly remembered as it is. It was also shareware, making it far less expensive, both when it was new and nowadays, than most edutainment titles.