Grasshopper problem: 8/8/8/8/8/8/5gPp/5K1k w 0 iiii - V. Onitiu, Die Schwalbe 1929.
+ Wikipedia maybe https://en.wikipedia.org/wiki/Grasshopper_(chess)

Shako, also known as UniEed Chess (Jean-Louis
Cazaux, 1990). Board 10x10; extra pieces are
Elephant (moves one or two squares
diagonally, may leap intervening square) and
Cannon (as above); CC on a1/j1 and a10/j10,
ERNBQKBNRE on ranks 2/9, 10xP on ranks
3/8. The name means chess in Esperanto.
(Cazaux)

Shogi + Makruk/Thai chess --> see on Pychess

Interesting:
Monochrome Chess (Proprietary game,
Looney Industries; Andrew Looney, 1996).
Usual men and array but pieces are all of the
same colour. A man is controlled by the player
in whose half of the board it stands. Thus after
e4-e5, the pawn changes sides and reverses
direction. When you capture (by definition, in
the opponent’s half) there can be no recapture
as the piece has changed sides. You may not
immediately reverse an opponent’s move. The
king has no royal powers but can castle. The
men are allocated points and the object is to
have the most points (in pieces captured) when
the game ends, which is usually when the
players agree or when one half of the board is
empty. Values: King=10, Queen=8, Rook=5,
Bishop=4, Knight=3, Pawn=1. A related game
Martian Chess is described in chapter 38.
(Proprietor’s rule sheet, Variant Chess 39)

Chakart :)
https://www.chessvariants.com/crossover.dir/koopachess.html

Diamond Chess [Rynd] (J. A.
Porterfield Rynd, 1886)  --> Berolina2 ?
https://www.chessvariants.com/rules/diamond-chess

Bicolour Chess (Gabriel Authier, 1958). v1 et v2 : (Roméo Bédoni, 1958) 
Kings are subject to check and checkmate by
own as well as opponent’s pieces. The Q and
QN are interchanged in the array
.
v2: y but a player may capture his
own men (TODO: only v2?)

Koth : king of the hill, king cannot move into check, giving check is forbidden (no checkmate).

Berolina Grid Chess, also known as
Gridolina (originator not noted). A
combination of Berolina and Grid Chess.
Better than Grid Chess since Berolina pawns
cross grid lines more easily. Described in
World Game Review 10 as the most popular of
the NOST combination games. (Nost-algia
150, also Nost-algia 112 ‘not seen’) 
--> pourquoi pas, mais faudra pouvoir tracer des lignes sur plateau (Ball, Koth, Sittuyin, celle-là, Rococo)

Contact (quoted by David Silverman, 1971).
White puts a knight on any square of an empty
chessboard. Black moves the knight and
places a marker on the square vacated. Play
alternates. The knight may only be moved to
vacant squares. The object is to make the last
move. The game can also be played with any
of the other pieces. (Your Move)

https://www.chessvariants.com/diffmove.dir/checkers.html --> move forward (Multhopp)
in 1974 by Hans Multhopp
https://www.chessvariants.com/diffmove.dir/checkers.html

Clockwork Orange Chess (Fergus Duniho,
1999). https://www.chessvariants.com/other.dir/clockworkorange.html
implem : pieces code, yellow/red, easy

http://abrobecker.free.fr/chess/fairyblitz.htm#football
Le gagnant est le premier joueur à marquer un but, càd celui qui arrive à installer une de ses pièces dans les cages adverses: d8,e8 pour les blancs et d1,e1 pour les noirs.

Recycle1 et Recycle2 (--> celle-là)
http://abrobecker.free.fr/chess/fairyblitz.htm#deplaceurdevivants
Philippe Rouzaud, Phénix 151-152, mai 2006): Un camp peut, à la place d'un coup orthodoxe, capturer une de ses pièces et replacer la pièce capturée immédiatement sur l'échiquier. Un roi peut rester en échec durant cette action. Une pièce déplacée sur l'échiquier peut mater. Un pion ne peut pas être déplacé en première ou dernière rangée. Un roi peut déplacer et être déplacé, y compris pour se soustraire à un échec. Le roque ne peut se faire que de manière orthodoxe.
Rouzaud-Banaddou: 1.Fxb2 (=f5) Dxc7 (=e6) 2.fxe6 dxe6 3.Txb1 (=b5) Dxe7 (=c7) 4.Txb2 (=a3) Dxf7 (=d6) 5.Txg1 (=g5) Dxg7 (=f6) 6.Txf1 (=f7)+ Rxf8 (=h4) 7.Fxb2 (=e8) Rxg7 (=c5) 8.Rxd1 (=f8)+ Rxh8 (=g7) 9.Dxg8+ Txg8 10.Txg8#

http://abrobecker.free.fr/chess/fairyblitz.htm#madrasi
Madrasi Chess, Abdul J. Karwathar, 1979): Deux pièces de même nature (excepté les rois) qui s'observent, se paralysent mutuellement en perdant tout pouvoir (déplacement, prise, donner échec ou mat) sauf celui de paralyser une autre pièce.
1.e4 e5 2.Cf3 Cc6 3.Fc4 Fc5 4.Cxe5 d6 5.d4 (5.Fxf7+ Rxf7 est légal; ou 5.Dh5 Fe6 immobilisant le Fc4) 5...Fxd4 6.Dxd4 dxe5 et la Dame blanche est perdue.