Here's my demo. Looking back at it I can't really see a specific linchpin or technique to hint at; it was more trial and error.
Obviously there's a general approach you should have figured out to avoid being completely overwhelmed by roaches:
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×Get each roach in turn on the hot ortho tile so it wants to move diagonally and is blocked from doing so.
But there are a few different ways to do that depending on what didn't get me killed at each particular point:
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×Rely on a subsequent roach being on a pressure plate to raise a couple of yellow doors.
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×Do the blocking with one yellow door and another roach.
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×Use the speed potion to get ahead and step on a pressure plate yourself, then step off in the right direction to manoeuvre the hot tile roach.
