I spent/wasted/lost considerable time on this puzzle. I would like to offer a minor correction to CF's nearly perfect description above. The clues are tough, but to qualify as "oblique" they must at least touch, intersect somewhere. I think the correct geometric term here is "skew" intersecting at no point and not in the same plane. The LEAPS required to proceed in the puzzle soon exceeded my reserves of enthusiasm.
A cool puzzle, but way, waaaaay too little reward for the effort.
Most times
this is more my speed.