Kids are never going to be happy with just assembling the bricks into the Star Wars configuration outlined in the directions. Initially it's a challenge to put kits together according to the plans but once they're built any clever kid is going to mod them and eventually dismantle them and use the parts for something new entirely. That said, there are the Technics kits which have functional components that are largely useless outside of their intended configuration unless you have a massive amount of gears and spare pneumatic parts.