> Littleman programs are two dimensional and place a heavy emphasis on spatial reasoning - your little men must physically walk over instructions to execute them

Is the thought here that since AIs are worse at spatial reasoning, solutions to the contest are more likely to be human-generated?

I'm not personally convinced; I think it means the program could be modeled as a graph and likely analysed, or at worst brute-forced, by a determined AI. But I suspect an AI armed with a Python graph library could build this quite well. That said -- this is speculation. And I have no idea how is best to tune a content for humans not AIs.