It doesn't have to be robots: In my opinion, Mixels looked kinda close to a bionicle setting at first. Think about it: You've got different clans, all based off elements. You've got the combining idea (Like the Kaita and Nui in 2001-03). The focus is on the heroes, although the badguys are there too. You've got the different locations, all related to their elements and admittedly looking quite interesting. Then the characters themselves, all looking alien, goofy, and elemental... ...But then came the TV show. It was an epic flop from the first. It was clear this wasn't going to be another Bionicle, but more of a weird spongebob. Another epic flop of a theme in what's been a history of epic flops since Ninjago started. So it doesn't need to be robots/biomechanical beings. It just has to take the storyline seriously, at least to the extent Ninjago did.