Looking in Edmonton for chess sets for sale, I saw that someone had "Dukes
Chess" for sale.
I did a Google Search, and found out that this was a proprietary chess variant.
It was on an 8 by 9 board.
White's layout was changed by adding the Duke between the King and the King's
Knight, and on the King/Duke side, the Knight and Bishop are swapped, so that
both Bishops are of opposite colors.
On the Black side: Black's Duke is opposite White's Queen and vice versa. But
the board doesn't have central symmetry - the Knights are opposite Knights, and
the Bishops are opposite Bishops.
The Duke moves on Queen lines, but it can only move 1, 2, or 3 spaces. And it
can only capture, again on Queen lines, by moves of 2 or 3 spaces.
The company making the game appears to have failed and disappeared.
While, unlike, say, Chancellor Chess, this game could have been quite playable, since the Duke is not so overpowered as to unbalance the game, it's not surprising that the game failed to make a splash. Why invest effort in learning
how to play such a game well, when Chess exists with such a large community
behind it, and is so similar?