I applied for a QA position at a company that uses time-of-flight cameras with industrial robots. I researched their solution, got a sense for its architecture

I applied for a QA position at a company that uses time-of-flight cameras with industrial robots. I researched their solution, got a sense for its architecture, and started toying around with building a Flatland-style version of their product. I figured that a demo like that would stand out much better than anything on my resume. They rejected my application before I got too far with the demo, which would have taken me a lot more than six hours to finish. Although it might have been an interesting addition to my Github repo, it was kind of tailored to this one company. I'm not disagreeing with the OP, because I probably wouldn't find an interview project nearly as fun. I wonder, though, whether anyone has been successful with a one-off, company-specific project like this, as opposed to a general portfolio of projects that you've made over the years.