What I described is really more of a pointcrawl with only two points (the town and the dungeon), not much of a sandbox. The "quite strong direction," such as it is, can be framed as "go to the dungeon" since that's where adventure can be found. The kids aren't that young in my view, and certainly no younger than a lot of kids who started off in the town-to-dungeon model of the early days of D&D. I bet they do just fine.Ignore this. You have a couple of quite young kids and a reluctant player just along for the ride. They need quite strong direction, not a sandbox.