Have you checked out HEXBUG VEX Robotics?
VEX Robotics machines are compatible with one another. "HEXBUG believes in using the fun of robotic toys to teach children important STEM principles through hands on learning." As a parent it is the kind of toys I like to buy my kids. When you purchase these HEXBUG VEX Robotics toys, you are giving your child a tool to learn and play..it's truly a win - win! We have always been a fan of HEXBUG toys and these are on our wish list this year for sure.