Notation in Mystic Chess

As pawns can be dropped on the board and pieces can be upgraded, the notation in Mystic Chess slightly deviates from standard chess. Any moves that are specific to Mystic Chess can be identified with a @ before the square name. For instance dropping a pawn on e2 is written @e2, whereas upgrading that pawn to a bishop is written B@e2. This notation is similar to the Crazyhouse chess variant.

Here is the notation of a full game:

Mystic chess game: Simon - Guillaume, 08/01/2020

1.@d2 @d7 2.@e2 @f7 3.@f3 @e6 4.B@f3 B@e6 5.R@f3 R@e6 6.Q@f3 B@f7 7.Qa8+ Ke7 8.Qa3+ @d6 9.B@d2 Bh5 10.@f3 B@d6 11.Qc3 R@h5 12.B@f3 Rc5 13.Qg7+ Kd8 14.Bg4 Re7 15.Qh8+ Kc7 16.Qa1 Q@c5 18.Qa5+ Qxa5 19.Bxa5 Kc6 20.Bf3+ Kb5 21.Bd2 Rh7 22.R@f3 Rh1+ 23.Kf2 Rh2+ 24.Kf1 R@d6 25.B@e2+ Kb6 26.Bf4 Rh1+ 27.Kg2 Reh6 28.Bxh6 Rxh6 29.Rb3+ Kc7 30.Rc3+ Rc6 31.Rxc6+ Kxc6 32.Kg3 Kc5 33.Kf4 d5 34.Ke5 d4 35.Ke4 Kd6 36.Kxd4  1/2-1/2   

For those who cannot yet play blind Mystic Chess, here is an animated diagram of the game.

Of course this particular game is not free of blunders, but it gives an idea of how it works. Among around 10-15 Mystic Chess games played so far, this is the first one that ended in a draw. Better yet: every game so far has been unique. It is good to see this game does not suffer yet from heavy theory like the standard chess game. It often finishes in all sorts of pawn, bishop or queen endgames, which is a lot of fun. Of course, as long as one player still has a coin left, he can buy a pawn and convert the position into a winning endgame. So it is wise to keep at least a coin quite long in your stock...

Rules

"Mystic Chess" is a chess variant using an orthodox chess board with unorthodox rules.

The game differs from the standard chess game in the following rules:

• The starting position only includes the White and Black kings, at their standard positions (on e1 and e8 respectively). The remaining chess pieces are placed beside the board for further use.

• Each player starts with 20 coins, to be placed in front of him, which are used to buy pawns and upgrade pieces. In case no physical coins/tokens are available, a sheet op paper can be used to monitor the number of coins remaining for each player, which should be visible during the full duration of the game. 

Starting position, with 4 stacks of 5 coins on each side

• At his turn, a mystic chess player has the choice between 3 different actions:

1. Play a standard chess move
2. Buy one pawn with one coin. The coin should be removed from his personal stock and put aside. The pawn can be dropped in any unoccupied square between ranks 2 and 4 for White, and between ranks 5 and 7 for Black.
3. Upgrade one piece according to the standard evaluation used in chess: a Queen is worth 9 points, a rook 5 points, a bishop or a knight 3 points and a pawn 1 point. The upgrade should be done progressively, which means a pawn can only be upgraded to a bishop or knight (by paying 2 coins, as it is the difference in evaluation between the 2 pieces). Then the bishop or knight can be upgraded to a rook by paying 2 extra coins, which in the next turn can be converted into a Queen by paying 4 extra coins.

Action 2 should be performed at least 3 times before action 3 can be performed. This allows building a basic pawn structure before being attacked by the opponent's pieces. So in practice the players have to buy at least 3 pawns before upgrading them to higher pieces. After these 3 first pawns are bought, any number of pieces can be upgraded, as long as enough coins are available to pay the upgrade. There can however not be more pieces of one type than in a standard chess set. For instance, White or Black are not allowed to upgrade 3 pawns to have 3 bishops at the same time on the board. It is allowed to have two light-squared or two dark-squared bishops. 

A pawn reaching the 8th rank can be promoted  as usual to a piece (bishop, knight, rook or queen), but only as long as it is still available (so not to a queen if a queen is already on the board, for instance if bought earlier with coins). Pieces than have been captured or upgraded to a higher piece are going back to the stock of pieces available for upgrade with coins or promotion of pawns on the last rank.

As in standard chess, the winner is the player who can checkmate his opponent.