9x10 chess with centaurs axed ideas

[Admin]

Testing the game
The game was first played against the AI on this site, the AI was easy to defeat (does not seem to be programmed well).

https://www.omnichess.club/variant/f16f22ff-5652-42d4-9a32-bb566e8f19f2

I decided to instead play against myself via inkscape using the undo feature in the case i made some blunder, i also used stockfish for the endgame (when i could get an analog 8x8 position).

I did test queen vs rook endgame on 10x10 board via pychess.org and the rook was captures move #29 but it's unclear how well fairy stockfish defended that (i did use deeper than standard analysis).

[Event "?"]
[Site "https://www.pychess.org/analysis/grand"]
[Date "2022.06.04"]
[White "?"]
[Black "?"]
[Result "*"]
[Variant "Grand"]
[FEN "10/4k5/4r5/10/10/10/10/5Q4/4K5/10[] w - - 0 1"]
[SetUp "1"]
1.Kd3 Rd8+ 2.Kc4 Rc8+ 3.Kb5 Rb8+ 4.Kc6 Rc8+ 5.Kd7 Rd8+ 6.Kc7 Rg8 7.Qh5 Rg7+ 8.Kd6 Kf8 9.Ke6 Re7+ 10.Kd5 Re8 11.Kd6 Rd8+ 12.Kc7 Re8 13.Kd7 Re10 14.Qh8+ Kf9 15.Qh7+ Ke9 16.Qg7+ Kf9 17.Qf7+ Kg10 18.Kd8 Rf10 19.Qg8+ Kh10 20.Ke9 Rg10 21.Qh8+ Ki10 22.Kf9 Ra10 23.Qg8+ Ki9 24.Qg7+ Ki8 25.Qg6+ Ki7 26.Qg5+ Kj6 27.Qj2+ Ki5 28.Qi2+ Kh4 29.Qxa10 Kg5 30.Qa4 Kf5 31.Qd4 Ke6 32.Qe4+ Kd6 33.Ke10 Kd7 34.Kd9 Kc7 35.Qe6 Kb7 36.Kd8 Kb8 37.Qb6+ Ka8 38.Kc8 Ka9 39.Qb9# *

The bottom rank was never used so it would have been the same on 9x10 (likely easier in many positions).

 

[Admin]

A deeper look at double promotion
Let's say you are allowed to place a knight xor bishop on the square the pawn was prior to promotion if you do not promote to queen or centaur.

That would allow players to for example give check with a bishop while for example threatening the queen with a knight.

This also means that threatening the piece the pawn goes to for promotion might not prevent promotion from being beneficial since you might still get a useful bishop or knight out of it (while your rook xor knight xor bishop got captured).

It wasn't hard to come up with a position for each promotion where said promotion is the only willing move:

Of course the game can also be played with standard chess promotion rules (no promotion to centaur) resulting in there being position for all promotion types where said promotion is the only willing move (bishop and rook will rarely be used though).

 

[Admin]

Early promotion
We might for example want to allow promotion to bishop, rook or knight when the pawn ends up one move away from the final promotion (to queen or centaur).

https://www.omnichess.club/variant/691a20b8-37d5-4947-af1d-78c53d7949c8

Player will choose between promoting now to bishop/rook/knight or hold out to maybe get a queen or centaur. Here only one promotion is allowed so if you take a bishop now (example) you will not be able to promote that bishop to anything else.l