Thanks — the detail about tracing straight pipes backwards was especially useful. I’ve added puzzles 13–36 while keeping the original 12 unchanged. If you feel like trying one or two of the new puzzles, I’d be interested in whether finding the route feels satisfying, too obvious, or frustrating. No need to replay the earlier ones or chase fewer turns.
From what I remember, it's basically because some details change from straight pipes into right-angle bends, which makes the most obvious predicted route incorrect and forces you to take a detour—or else you just can't spot the so-called predicted route at first glance. Personally, I actually enjoy that sense of confusion more.
