Not sure if its an alternative, but Lego Boost is awesome and not well known yet. https://shop.lego.com/en-US/LEGO-Boost https://shop.lego.com/en-US/LEGO-Boost.

Not sure if its an alternative, but Lego Boost is awesome and not well known yet. https://shop.lego.com/en-US/LEGO-Boost https://shop.lego.com/en-US/LEGO-Boost. I'm not sure if its supposed to replace Mindstorms or is an alternative track for ipad driven robots.