Hello! I recently made an account and spent some time surfing the forums before I decided to make a post of my own. On the wizards forums, and most likely elsewhere, numerous gamers who role-played for years need some help changing DnD so that their 5-10 yr olds can play. Is there any advice for those of us who want to introduce our kids Planescape, which is arguably a completely new game with it's own learning curve? As a boy I remember having a hard time wrapping my head around the Lion, Witch and Wardrobe which had just the one mature portal!
Ironically, one of the main reasons I really like Planescape is because it generally appeals to a more mature audience, considering the emphasis on philosophical conflicts and gritty "lives-are-cheap" feel of the Blood War and other horrors of the multiverse.
That being said, I don't see why you can't change it be to more suitable for young children. I'd say emphasize the idea of exotic creatures walking about in the cosmopolitan setting of Sigil, and the thrill of jumping portals to new and strange worlds where there's inverted lands above you (Bytopia) or clockwork islands (Mechanus).
Have tea-parties with slaads, watch modrons build polyhedral buildings, and race around the hoop of Sigil!