Napoleonic game resembling solitaire? (4)

I believe the answer is:

solo

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'napoleonic game' is the definition.
'solo' can be an answer for 'game' (I've seen this before). I am not sure about the 'napoleonic' bit.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for solo that I've seen before include "Aline in Oslo" , "Han - (Star Wars); fly unaccompanied" , "One-person performance" , "Unaccompanied - card game" , "Game for four" .)

I've seen this clue in the Evening Standard.

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