Spoiler: Hints - holding a draggable can freeze a bot - the lower bot must be froze (not turning) for another R to pass above - R's legs will grow if facing stairs - a lone brick is a trap Spoiler: Video Solution
I picked my winning gameplay first time round and was racing for a superfast win then forgot about the trap on the way back. Aaargh! My win was quite different. Never used the head of B. Spoiler: Alternative when Z walks across a raised PillarR heading for head of pillarB, instead I quickly dropped draggable and let Z fall when PillarR walks forward. Took B down he same way.