What is the complicated part? Is there a lot of math? Is it slow? A lot to keep track of? Gaming of all kinds is by DS's #1 interest, so interest is intense. I don't think we have yet met a game he could not learn, but we haven't yet bought any of the top-level Eurogmes.

I know someone has to be dungeonmaster, and that that part takes a lot of planinng. My DH is willing to do this. He played the game a little as a teen, though he was not really into it by any means.

I will look at Mouse Guard and especially Dungeon World. Something extensible would work well for us in that it would suit DD10's desire to create. Her monsters are very scary and awesome. (She has one called a "sklate"--looks like a human, but its pupils are slits and it has no lips. It's telepathic, and if you get too close to one when you are under 10 years old, you will automatically kill someone you love the day you turn 11. The worst part is that you then regain your senses and realize what you've done, just before you die. Yeah, DD has quite the imagination!)