This puzzle is a combination of an assembly puzzle and a burr puzzle. It was designed by Steve Johnson and was inspired by Steve Winter's Soma's Revenge
. The Soma's Revenge constsis of 14 parts, six "inner" and six "outer", which are all based on the classic Soma pieces, all of which have to be pushed together, then slid like burrs to form the final cube.
The Sword in the Soma has 15 pieces, the extra piece being the sword.
File comment: SitS1
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Again, all parts except the sword are based on the classic Soma pieces. The large coloured parts are standard pieces, with the addition of slots and cavities which are just big enough so that the inner black pieces can be interted into them.
File comment: SitS6
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File comment: SitS5
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Originally the "sword" was just a plain bar, so I jazzed it up a bit and added a hilt:
File comment: SitS4
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There is just one solution in which all of the pieces can be put together and then the sword inserted almost all of the way through. It the burr terminology it is classified as a 22.214.171.124.126.96.36.199.188.8.131.52.4 (= 25 moves) puzzle and Ken describes it as "very difficult".
This puzzle (with Ken's permission) is for sale on my Shapeways Shop