Like many people who grew up in the halcyon era of paper-based RPG's, I know have young children. Both of mine are school-aged, and are exposed in some way to my playing roleplaying games. Finding a way to introduce the fun of using your imagination, as well as developing problem-solving skills, teamwork, and reading ability through RPG's has been, to date, a bit of a challenge. Most RPG's are geared towards teenagers and my own attempts at doing some "kid-friendly" games have been disastrous.
The RPG industry seems to be waking up to this. Wizards of the Coast created Monster Hunters, a very whittled down and almost completely peril-free version of Dungeons and Dragons. Troll Lord Games made Harvesters, where the players play farm and woodland creatures anthropomorphizing them into furry D&D-esque characters.
One RPG that I became aware of recently was Meddling Kids, by Pandahead Productions, which as you might expect is a RPG depicting the Saturday morning cartoon "kid mystery" shows like Scooby Doo Where are You or its many clones, e.g. Speed Buggy, Jabberjaw, Josie and the Pussycats, etc. The game states it is for ages "7 and up" which is about right. PC's have four stats, reflecting their strength, dexterity, intelligence, and health. Each PC must also choose an "archtype" which corresponds broadly with one of the character types from the show: the burly person, the goofy person, the smart person, or the attractive person (which sadly gets called "Fluff," making me wince slightly). What a player can not play is the "Wild Card" which is reserved for the GM to play as an NPC. The Wild Card can be anything the GM imagines: an animal, alien, robot, ghost, or in the case of the sample "Clique" a primate possessed by the ghost of a 17th century pirate named "Captain Bingo." The Wild Card is reserved as an NPC to allow the GM to nudge the players in the right direction, provide comic relief, or just to keep the plot rolling. Conscientious GM's should be careful not to use the Wild Card to completely run the story, or to introduce annoying nephews later in the campaign.
Which does bring me up to one interesting rule/dynamic, namely combat. In an early episode of Scooby Doo Scooby, in a rare fit of non-snack related bravery, rushes a villain while snarling and barking. This particular villain lacked a supernatural appearance and raises for the adult viewer a pretty obvious question: character flaws aside, why not just jump a monster with an improvised weapon and beat him down?
In Meddling Kids, they answer this by simply saying you can't. Period. "Fighting never solves anything," the rules state. Instead the players must improvise traps and make a roll to see how it works (failure almost always involves the Wild Card in the narrative). If this seems formulaic, I think this is no mistake, given how formulaic its founding material is. And I don't think that given the game's goal of introducing children to RPG's this will be much of a problem. Meddling Kids is a gateway game--I can't see playing it for years but it could be a good tool to familiarize children with the concepts before moving on to fantasy or superheroes or something a little more complex.
Now the downside. The book, which clocks in at 96 pages, is incredibly padded. It has large illustrations, a large font, and several pages on the history of cartoons. This is space that could have been used to provide additional story ideas to complement the single adventure "The Dragon's Eye" which is too closely tied to the sample PC's in the book (it is even subtitled "The Origin of Captain Bingo.") A great supplement would be half a dozen adventures that could be used by any Clique.
You can purchase Meddling Kids from DrivethruRPG.com