Another Unusual Mate in One Here is another mate-in-one of my own i.e. a not quite usual one...
    [title &quot;Mate in one&quot;]
    [FEN &quot;3b4/R3P3/2kPR1n1/P1p1n3/4K1p1/2Nr4/5p2/1b6 w KQkq - 0 1&quot;] 

Imagine, you walk into a chess club, an abandoned chessboard hangs out on a table. You take a look at the position. You don't know where white or black is, who to play, yet one thing is certain: there is checkmate in one move...
There are two checkmates per orientation:
    [title &quot;Mate in one&quot;]
    [FEN &quot;3b4/R3P3/2kPR1n1/P1p1n3/4K1p1/2Nr4/5p2/1b6 w KQkq - 0 1&quot;] 

1. exd8=N#

and
    [title &quot;Mate in one&quot;]
    [FEN &quot;3b4/R3P3/2kPR1n1/P1p1n3/4K1p1/2Nr4/5p2/1b6 b KQkq - 0 1&quot;] 

1... Rxc3#

and
    [title &quot;Mate in one&quot;]
    [FEN &quot;6b1/2p5/4rN2/1p1K4/3n1p1P/1n1RPk2/3P3R/4b3 b KQkq - 0 1&quot;] 

1...c6#

and
    [title &quot;Mate in one&quot;]
    [FEN &quot;6b1/2p5/4rN2/1p1K4/3n1p1P/1n1RPk2/3P3R/4b3 w KQkq - 0 1&quot;] 

1. e4#