Hmm, The Oregon Trail comes to mind as an educational game which was quite fun, and clearly sold to a lot of institutions. Do you have any thoughts on how that came about?
And it doesn't matter how much of it was sold to institutions. What matters is how many users benefited from this game and similar ones (Railroad Tycoon, Civilization, etc. come to mind).
factoria is another good one that's really really fun and can also be really really educational if you think about the materials and resources and how you combine them. also if you really want to go crazy with it learning some math will help you fully optimize your factory but it's some pretty complicated math, at least for me.