Let me add to the plaudits. This is a very challenging hold, clever and quite enjoyable. Thank you for creating it Larrymurk.
I am, however, stuck. I can clear out many of the tar chambers and am not worried about the two near the entrance but the two east side chambers (1+2) have me flummoxed.
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×The best I can do is one turn late and involves cutting half of one tar mass and retreating to close the doors.
Plainly there is a way that works that I am missing. While I am hopeful that the act of requesting help will have its usual effect, any hint would be welcome.