Tom I wouldn't have got this except I saw the solution to Forest Path. Nice tool to have in the locker!
Tom andy I think it's very hard until you know this mechanism and then very easy after! Tricky to grade it. Maybe have an earlier level where you have to fill in one or two missing pieces so that players can gain familiarity.
andy Tom Yeah this one is supposed to be training for the extremes, so maybe it goes near the end of hard, and you figure it out because there are very few other things you can even try.