About a 3/4 day single interview. Interviewed with a few different level of people including HR, some Sr. Level Engineers and a few Mid Level Engineers. Both levels of engineers asked technical questions. This was when they were Robotics Research LLC, maybe it is different now as Forterra. A lot of the questions were issues they had in the past on systems they designed. Felt they were a bit of a "gotcha" style. To expect interviewees to come up with the exact solution that solved the problem within a few minutes of introduction to an entire system a team had spent months or years to design felt a bit silly. I got most of these questions at least partially correct, but I never got a job offer...or an answer as to if I got the job. This was over 3 years ago filling out to keep glassdoor access, but I assume I didn't at this point. At the end of the interview it sounded like they were going to send an offer. Basically saying they were and if I needed it before a certain time with competing offers, one of the Sr. Engineers said "see you soon" when I was leaving. After that though the HR person went dark and never replied to any of my follow ups. Interview was fine, but difficult. But let candidates know if you aren't hiring them rather than waiting. Especially if you tell them you are sending an offer.