2 yrs into a 1on1 campaign with my 9yr old son. Supplied him with a party: 1 Lhankor Mhy, 1 Issaries trader, a Storm Bull, a Humakti. He later switched the Humakti for a Humakti duck. I'm so proud!
Started using the FATE system and plundering the RQ2 scenarios (Trollpak, Borderlands). Ran River of Cradles/Troubled Waters, which I adore. Although it was awesome for magic (I let characters use runes as skills), It didn't have enough granularity for the combat so I switched to 13AiG when it became available. This is a rollicking combat system! It has that sense of danger and flavor from RQ2, only this time the PCs are truly heroic. Would love to do Snakepipe Hollow with 13AiG but the PCs are too busy beating up Lunars. !Holy ship! moment when the duck took out the Greater Jackobear at Rabbit Hat Farm in one round. (350 HP) Was necessary, because the Storm Bull had been Harmonized. The Humakti are deadly but brittle, while the Storm Bull has different berserker powers every round and generally gets the most beat up of all the characters, only to shrug it all off at the end of the combat.
We also tested out a trickster, and are trying out a troll Hombobobom devotee. These are loads of fun. My son particularly liked the Fustercluck power (he has no idea) and he really got into the roleplaying by having the trickster run around in a panic for most of the combat. The Trickster class is IMHO a major contribution to Gloranthan roleplaying. Highly recommended. IF you can stand having a trickster in your party....
Trying to remain within the Canon, will probably have to handwave some dates. Avoiding major commitments by starting out with isolated scenarios. Now that I have a better sense of what we can both handle, am ready to integrate more firmly into Canon.
I also struggled with starting out. 7 year olds are not interested in reading a lot of background material and I don't have a lot of time for prep. In this sense, Troubled Waters, combined with Borderlands, is a very good starting point. Minimize the background stuff; say the characters are on the run and perhaps partly amnesiac, and have them get to know the world and the communities as they travel upriver. Now the party is planning to rescue Kallyr from a Lunar Hell (not Canon, obviously) and I plan to use that to shoehorn them into parts of the Colymar campaign from the Sartar Companion etc books. Tie them into a community etc.