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This page is written by the game's inventor, Carlos Cetina.

Cetina Random Chess

Carlos Cetina from Mexico invented this game in 1998. He based it on Fischer's form of Random Chess, and made some changes. In particular, he added the piece of Sissa, which also appears in some other games by Cetina.

Rules

The game is played on an 8 by 8 board.

Each player has:

The purpose for replacing a rook and a knight for a sissa and a chancellor is to complicate the game and it is a consequence of this wounding question: if the traditional arrangement of the pieces is broken, what is the case for the rooks and knights be twice?

The starting position of the pieces (the non-pawns) is determined by hazard: a raffle per each player, that is, there are two independent raffles. This has a purpose: to avoid that the players could follow one respecting another symmetric schemes of development at the opening, and in consequence they have FROM THE BEGINNING to effort to encounter the best strategy for the development of their pieces.

The raffles, CONTRARILY TO FISCHER'S PROPOSAL, are absolute, genuine raffles, that is, they are accomplished WITHOUT RESTRICTIONS, WITHOUT CONDITIONS, and if the bishops fall on squares of a same color, then the BCR holds. (See below.)

Castlings are absolutely suppressed. If, in particular, the king falls on e1/e8 and the rook on a1/a8 or h1/h8, the castling may not be done.

Moves of pieces

King, queen, rook, knight, and pawns move as in orthodox chess, except that pawns also may promote to sissa or chancellor, i.e., a player moving his pawn to the last row can choose to promote it to queen, rook, knight, bishop, sissa, or chancellor. The chancellor has the combined moves of rook and knight.

A sissa moves like the knight in Coherent Chess (another chess variant by Carlos Cetina), as follows: in one turn, first, the sissa moves one or more squares like a rook or a bishop, and then the sissa moves the same number of squares like the other of the two (bishop or rook.) So, the sissa has the following options:

  1. First, it moves a number of squares as a rook. Then it makes a corner of 45, 135, 225, or 315 degrees, and then moves the same number of squares as a bishop. All squares that are passed by must be empty, i.e., a sissa does not jump over pieces.
  2. First, it moves a number of squares as a bishop. Then, it makes a corner of 45, 135, 225, or 315 degrees, and then moves the same number of squares as a rook. Again, all squares passed by must be empty.
See below for an example. (The white sissa has the possibility to take the rook or the queen.)

Bishop move as in orthodox chess, except when they start on squares of the same color. In that case, the bishop conversion rule (BCR) holds: In this case, bishops have, in addition to their normal diagonal movement, one extra possibility (which is, in a certain sense, also obligatory): the bishop moves one square horizontally or vertically at the first time it moves during the game. This may be done only once, with one of the players bishops. Also, for one of the bishops of the player, the first move made with this bishop must be of this special type. This move is called conversion. Note that a player may choose which bishop he converts, but if he makes a normal move with one of his bishops, the first move made with the other bishop must be a conversion move. Note also that a player never can make more than one conversion move in a game, and a promoted bishop does not make conversion moves. It is possible to take a piece of the opponent by conversion. (See also a more detailed description of this `Bishops Conversion rule'.)

Sample games

White: Carlos Cetina                    Villahermosa, Mexico
Black: Angel Eboli                      April 20, 1998
Comments by Carlos Cetina 

                      +-----------------+
                     8| q r b c s k b n |
                     7| p p p p p p p p |
                     6| . . . . . . . . |
                     5| . . . . . . . . |
                     4| . . . . . . . . |
                     3| . . . . . . . . |
                     2| P P P P P P P P |
                     1| S R Q B B N K C |
                      +-----------------+
                        a b c d e f g h
NOTE: After every sissa's move it's indicated between parenthesis the path by which the sissa is moved from one square to another. If there are more than one moving path, then they are separated by a period. If the sissa moreover gives check, then first are indicated the moving paths followed by the checking paths, separated by a diagonal. That is: (moving paths / checking paths). 
 1.e4    b6
 2.Bf3   Bb7
Now the g8-bishop must be converted. Consequently, it doesn't cover neither f7 nor h7. 
 3.d3    d5
 4.exd5  Bxd5
 5.Cg3   Ng6
 6.c4    Bb7
 7.Bxb7  Qxb7
 8.Bc3   Nh4
 9.d4    Sd6 (e8-d7-d6)
10.Qc2   Ng6?
There is to consider this move as a serious strategic error. It's imprescindible, urgent to develop the g9-bishop. So, the correct move is 10. ... g6 following by ...Bg7 and ...Nf5, after which Black would have a solid structure. 
11.Re1   Sxc4 (d6-d5-c4, d6-c5-c4)
It is attacking to the c2-queen by c4-a4-c2 and c4-e2-c2, although the queen is protected by the a1-sissa by a1-b1-c2. 
12.Qe2
Double threat: to c4-sissa and mate in two, by 13.Cxg6+ ... 14.Qxe7# 
12. ...  Se8 (c4-c6-e8)
Now the sissa covers the e7-square by e8-d7-e7. 
13.Qh5   h6
14.Cf3   Nh8
15.Se3 (a1-c1-e3)
15. ...  Ce6
16.Sf5 (e3-e4-f5, e3-f4-f5)
16. ...  Cg5
17.Cxg5  hxg5
18.Qxg5
Threatening 19.Rxe7, and if 19. ... Sxe7??, then 20.Qxe7#. Note that 18. ... e6 is not possible because of the f5-sissa would give check by f5-c5-f8. 
18. ...  c6
19.d5
Threatening mate in two: 20.Bxg7+ Bxg7 21.Qxg7# 
19. ...  Ng6
20.Ng3   Sd6 (e8-d7-d6)
21.Sh5 (f5-h3-h5, f5-f3-h5)
The idea is to avoid an early sissa's exchange. 
21. ...  Sxd5 (d6-c5-d5, d6-e5-d5, d6-e6-d5)
22.Nf5   Sxg5 (d5-d2-g5)
It's also possible 22. ... Sxh5 by the path d5-d1-h5. 
23.Sxg5 (h5-h6-g5, h5-h4-g5, h5-g4-g5)
Now the threat is 24.Bxg7+ Bxg7 (24. ... Ke8 25.Nd6+) 25.Sh7+ (g5-h6- h7 / h7-g8-f8) Kg8 26.Sxg7+ (h7-h8-g7, h7-h6-g7 / g7-f8-g8, g7-h8-g8, g7-h7-g8) Kf8 27.h4 e6 28.h5 exf5 29.Sxf5+ (g7-f6-f5 / f5-c5-f8, f5-c8- f8) Kg8 (unique) 30.hxg6 fxg6 31.Re8+! Kh7 [31. ... Rxe8 32.Sxb7 (f5- d7-b7)] 32.Sf8+ (f5-c5-f8 / f8-g8-h7, f8-g7-h7) Kg7 33.Rxb8 etc. 
23. ...  e5
24.Bxe5  Nxe5
25.Sxe5 (g5-e7-e5, g5-e3-e5, g5-g3-e5)
25. ...  Qc7
26.Sf3+ (e5-e4-f3, e5-f4-f3 / f3-a3-f8)
26. ...  c5
Obstructing the a3-f8 diagonal. 
27.Re7
Threatening 28.Sxf7# (f3-b3-f7 / f7-e8-f8). 
27. ...  Qxe7
Forced. It will be interesting to see the struggle sissa against R+B! 
28.Nxe7  Kxe7
29.Se5+ (f3-f4-e5, f3-e4-e5 / e5-c7-e7, e5-g5-e7)
29. ...  Ke8
30.Sxa7 (e5-c7-a7)
30. ...  g6
Some late! 
31.g3    Bg7
Too late! 
32.b3    Bd4
33.a4    Kd7
34.Sb5 (a7-a6-b5)
34. ...  Kc6
35.Kg2   Re8
36.Sa7+ (b5-a6-a7 / a7-b7-c6)
36. ...  Kc7
37.Kf3   Re6
38.Sb5+ (a7-a6-b5 / b5-c6-c7)
38. ...  Kc6
39.Sd1 (b5-d3-d1)
39. ...  Rf6+
40.Kg4
Or 40.Kg2 Rxf2+ 41.Sxf2 (d1-e1-f2, d1-e2-f2) Bxf2 42.Kxf2 Kd5 43.Ke3 f5 44.h4 = 
40. ...  Rxf2
41.Sc1+ (d1-d2-c1, d1-c2-c1 / c1-h1-c6)
41. ...  Kd5
42.h4    f5+
43.Kh3
Unique. Of course, 43.Kg5?? Be3+ 
43. ...  Rf3
44.a5
Looking for complications. 
44. ...  Rc3
If 44. ... bxa5, then 45.Sxa5+ (c1-c3-a5, c1-a3-a5 / a5-d8-d5, a5-a8- d5) 
45.Sd1+ (c1-c2-d1, c1-d2-d1 / d1-h1-d5)
45. ...  Kc6
46.a6
Looking for complications. 
46. ...  Rxb3
47.Sc1+ (d1-d2-c1, d1-c2-c1 / c1-h1-c6)
It is menacing to the rook at the same time by c1-c2-b3 and c1-b2-b3. 
47. ...  Rf3
Unique. Obstructing the h1-c6 diagonal. 
48.h5!
It's not possible 48. ... gxh5 because of the sissa would give check by c1-h6-c6. 
48. ...  b5
49.Sf7! (c1-c4-f7)
It is menacing to the rook by f7-b3-f3. 
49. ...  Ra3
50.hxg6  Rxa6
51.g7    Bxg7
If 51. ... Ra7??, then 52.Sxa7 (f7-a2-a7); and if 51. ... Ra8?, then 52.g8=S+ (g8-e8-c6) Rxg8 53.Se7+ (f7-f8-e7, f7-f6-e7, f7-e8-e7, f7-e6- e7 / e7-d7-c6, e7-d6-c6), winning the rook by e7-f7-g8 or e7-f8-g8. 
52.Sxg7 (f7-f8-g7, f7-f6-g7, f7-g8-g7, f7-g6-g7)
52. ...  b4
53.Sxf5 (g7-f6-f5, g7-g6-f5)
53. ...  Rb6
54.Sb3! (f5-d3-b3, f5-d5-b3)
54. ...  Kd5
If 54. ... c4?, then 55.Sa5+ (b3-a4-a5 / a5-b5-c6) Kc5 [the sissa covers both b5 (a5-a6-b5, a5-a4-b5) and d5 (a5-a8-d5)] 56.Se5+! [(a5- a1-e5 / e5-c7-c5, e5-e7-c5, e5-e3-c5); now the sissa covers b5 (e5-e8- b5), c6 (e5-d5-c6, e5-d6-c6) and d5 (e5-d6-d5, e5-d4-d5, e5-e6-d5, e5- e4-d5)] Kd6 57.Sxc4+ (e5-d5-c4, e5-d4-c4 / c4-c5-d6, c4-d5-d6); or 56. ... Kd4?? 57.Sd7+ (e5-e6-d7, e5-d6-d7 / d7-g7-d4, d7-g4-d4), winning the rook by d7-g7-d4 or d7-g4-d4. 
55.g4
The sissa covers h6 by b3-e3-h6. 
55. ...  Ra6
If 55. ... c4??, then 56.Sxb6+ (b3-e3-b6 / b6-c6-d5, b6-c5-d5); and if 55. ... Kc4??, then 56.Sb2+ [(b3-a3-b2, b3-a2-b2, b3-c3-b2, b3-c2-b2 / b2-b3-c4, b2-c3-c4); the rook is menaced by b2-f6-b6] Kd4 (obstructing the b2-f6 diagonal; note that the sissa covers b5 by b2- e2-b5) 57.Sa4+ (b2-a3-a4, b2-b3-a4 / a4-a1-d4, a4-d7-d4, a4-d1-d4), winning the rook by a4-a5-b6 or a4-b5-b6. 
56.Sb1+ (b3-d3-b1, b3-d1-b1 / b1-b3-d5, b1-d3-d5)
56. ...  Kd4
57.g5    Kd3?
Perhaps it would be better 57. ... Ra3+ 58.Kg4 Rc3. 
58.Sc1+ (b1-b2-c1, b1-c2-c1 / c1-c2-d3, c1-d2-d3)
58. ...  Kd2
Unique. The sissa covers c2 (c1-d1-c2, c1-d2-c2, c1-b1-c2, c1-b2-c2), c3 (c1-a1-c3, c1-a3-c3, c1-e1-c3), c4 (c1-f1-c4, c1-f4-c4) and e2 (c1- d1-e2, c1-d2-e2); if 58. ... Kd4??, then 59.Sc2+ (c1-b1-c2, c1-b2-c2, c1-d1-c2, c1-d2-c2 / c2-c3-d4, c2-d3-d4), winning the rook by c2-a4- a6; and if 58. ... Ke3??, then 59.Sc2+ (c1-b1-c2, c1-b2-c2, c1-d1-c2, c1-d2-c2 / c2-d2-e3, c2-d3-e3), winning the rook by c2-a4-a6. 
59.Sxc5 (c1-g1-c5)
59. ...  Ra3+
60.Kg4   Rc3
Black's position is quite hopeless. 
61.Se4+ (c5-d5-e4, c5-d4-e4 / e4-d3-d2, e4-e3-d2)
After this, Black resigned. There is no manner to save the game. For example, 61. ... Kd3 62.Sxb4+ (e4-e7-b4, e4-b7-b4 / b4-c4-d3) Kd2 63.Sd5+ (b4-c4-d5, b4-c5-d5 /d5-a2-d2, d5-g2-d2) Kc2 64.Sxc3+ (d5-d4- c3, d5-c4-c3 /c3-b3-c2, c3-b2-c2, c3-d3-c2, c3-d2-c2) Kxc3 65.g6 etc. 
White: Jose Martin Torres                Villahermosa, Mexico
Black: Carlos Cetina                     May 9, 1998

                      +-----------------+
                     8| r k b b c s q n |
                     7| p p p p p p p p |
                     6| . . . . . . . . |
                     5| . . . . . . . . |
                     4| . . . . . . . . |
                     3| . . . . . . . . |
                     2| P P P P P P P P |
                     1| Q K R N B C B S |
                      +-----------------+
                        a b c d e f g h
 
 1.g3    b6
 2.Nc3   Bb7
 3.e4    e6
If 3. ... f5?, then 4.Sxf5 (h1-f3-f5) 
 4.Bg2
With this move the bishops' status is definitively established; so, the e1-bishop is already of dark squares. 
 4. ...  f5
 5.Ce3   g5
 6.f4    Ng6
 7.exf5  Bxg2
 8.Cxg2  Sxf5 (f8-c5-f5)
 9.g4    Sf8 (f5-c5-f8)
10.fxg5  Bxg5
11.h4    Bf6
If 11. ... Nxh4?, then 12.Bxh4 Bxh4 13.Cxh4 Sxh4?? (f8-f6-h4, f8-h6- h4) 14.Sxh4 (h1-e1-h4). 
12.Ne4   Bh8
13.Bg3   d5
14.Ng5   h6
15.Rf1   Sd7 (f8-e7-d7)
16.Nf3   a5
17.h5    a4!
18.hxg6  a3
19.c3?!
Preferable 19.d4 
19. ...  Qxg6+
20.Kc1   axb2+
21.Qxb2  Kb7
22.Cf4   Qg9
23.Re1   Ra5
24.Cb4   Ca8
25.d4    c5
26.dxc5  Sxc5 (d7-d6-c5, d7-c6-c5)
27.Cd3
Or 27.Be5 Bxe5 28.Nxe5 (28.Rxe5 is not possible because of the c5- sissa would give check by c5-g1-c1) Ra3 29.Cd3 Rxc3+ 30.Cxc3 Sxc3+ (c5-a5-c3, c5-a3-c3, c5-e3-c3 / c3-e3-c1) 31.Qxc3 Cxa2+ 32.Kd1 Cxc3+ 33.Kd2 d4! 
27. ...  Sc4+ (c5-d4-c4, c5-b5-c4, c5-b4-c4 / c4-f4-c1)
28.Kb1   Sxb2+ (c4-b3-b2 / b2-c2-b1, b2-c1-b1, b2-a1-b1)
29.Cxb2  Bxc3
30.Cc2   Rb5+
31.Kc1   Qc8
32.Se7 (h1-h4-e7)      
32. ...  Bb2+
33.Kd1   Qxc2+
34.Kxc2  Ca3+
35.Kd2??
After 35.Kd1 Rc5!, White would be within the game yet. 
35. ...  Cxf3+
36.Kd1   Cd3+
37.Kc2   Cd4+
38.Kb1   Cd2#
 
     *   *   *   *   *   *   *   *   *   *   *   *   *   *

White: Jose del Carmen Miranda               Villahermosa, Mexico
Black: Carlos Cetina                         May 15, 1998

                        +-----------------+
                       8| s b k b r n c q |
                       7| p p p p p p p p |
                       6| . . . . . . . . |
                       5| . . . . . . . . |
                       4| . . . . . . . . |
                       3| . . . . . . . . |
                       2| P P P P P P P P |
                       1| S R C Q K B N B |
                        +-----------------+
                          a b c d e f g h
                          
 1.f4      b6
 2.Bf2     Bb7
 3.Cd3     e6
 4.b3      g5
 5.Sa4 (a1-d4-a4)
 
The b7-bishop cannot move along the h1-a8 diagonal because of the a4-
sissa would give check by a4-a6-c8.

 5. ...    Kb8
                                     
Liberating the b7-bishop.

 6.Bd4     Bf6
 7.Bc3     gxf4
 8.Cxf4    Ng6
 9.Cc4     Bxc3
10.dxc3    Bd5
11.Cd4     c5
12.Cb5     Ne5

It would be highly risking for Black 12. ... Bc6 13.Cd6 Bxa4 14.bxa4, 
when a5 and g3 would be very strong White's moves.

13.Cd6     Bxg2
14.Cxe8+   Cxe8
15.Bxg2    d5
16.Qd2     Qg8
17.Qf4     Qxg2
18.Qxe5+   Kb7
19.Kd2     Sc7 (a8-b8-c7)
20.Nf3     f6
21.Qh5     Ce7
22.Rg1     Qf2
23.Rg3

If 23.Rg7?, then 23. ... Cxg7 24.Sxg7?? (a4-d7-g7) Sxg7 (c7-g3-g7).

23. ...    Kc6
24.b4      b5
25.Sb2 (a4-a3-b2, a4-b3-b2)

Unique. If 25.Sa3?? (a4-b3-a3), then 25. ... Sxa3 (c7-a5-a3).

25. ...    Se3 (c7-e5-e3)

The threat is 26. ... Qxe2+ 27.Kc1 Sxc3+ (e3-e5-c3 / c3-e1-c1, c3-e3-
c1) 28.Kb1 Qd1#, when 29.Sxd1 (b2-c1-d1) is not possible because of 
the c3-sissa would give check by c3-b2-b1.

26.Nd4+

If 26.Ng1, then 26. ... Se4+ (e3-f3-e4, e3-d3-e4, e3-f4-e4, e3-d4-e4 
/ e4-e3-d2, e4-d3-d2) 27.Kd1 Qf1#, or 27.Kc1 Qe1#, or 27.Kd3 c4+ 
28.Sxc4 (b2-b3-c4) bxc4#

26. ...    cxd4
27.Rxe3    Qxe3+
28.Ke1

Unique. If 28.Kd1??, then 28. ... dxc3 with mate in the following 
move by ...Qd2 or ...Qg1.

28. ...    Qxc3+
29.Kd1     Qxb2

White resigns
                                              
                          *  *  *  *  *  

White: Carlos Cetina                     Villahermosa, Mexico
Black: Jose del Carmen Miranda           May 15, 1998


                        +-----------------+
                       8| c b r s b q k n |
                       7| p p p p p p p p |
                       6| . . . . . . . . |
                       5| . . . . . . . . |
                       4| . . . . . . . . |
                       3| . . . . . . . . |
                       2| P P P P P P P P |
                       1| B S B Q K C N R |
                        +-----------------+
                          a b c d e f g h

                          
 1.b3      Ng6
 2.h4      Nf4
 3.Cg3     c6
 4.Nh3     Cb6
 5.c4      c5
 6.Bc2     e5
 7.Nxf4    exf4
 8.Cg4     d5
 9.cxd5    Cxd5
10.Bxh7+!  Kxh7
11.Sxd5+! (b1-d3-d5 / d5-f5-h7)
11. ...    Sxd5 (d8-g5-d5)
12.Cg5+!   Sxg5 (d5-d8-g5)
13.hxg5+   Kg9
14.Qc2     f6??

Better 14. ... Qd6

15.Qh7+    Kf7
16.gxf6    Bb5
17.fxg7    Qxg7

Without comments!

18.Qxg7+   Ke6
19.Rh6+    Kd5
20.Qg5+    Be5
21.Qxe5#

                           *  *  *  *  *  
                          
White: Jose Martin Torres                 Villahermosa, Mexico
Black: Carlos Cetina                      May 23, 1998


                         +-----------------+
                        8| q c n b k s b r |
                        7| p p p p p p p p |
                        6| . . . . . . . . |
                        5| . . . . . . . . |
                        4| . . . . . . . . |
                        3| . . . . . . . . |
                        2| P P P P P P P P |
                        1| B Q C K S R B N |
                         +-----------------+
                           a b c d e f g h

 1.e4      e5
 2.d3

The e1-sissa is menacing to the e5-pawn by e1-a5-e5.

 2. ...    Cc6
 3.b3      Se6 (f8-e7-e6)
 4.f4      exf4
 5.Ce2     Bg5
 6.d4      f6?

Better 6. ... Cd6

 7.d5      Cd6
 8.Bc5

Now the a1-bishop doesn't affect the dark squares and its first move 
must be towards b1 or a2.

 8. ...    Se5 (e6-f5-e5)
 9.Bxd6    Nxd6
10.Qb2     Sg6 (e5-f5-g6)
11.e5      Nf5
12.exf6+   Kd8
13.Qe6     Ne3+
14.Cxe3    fxe3
15.fxg7    Sxe5 (g6-f6-e5, g6-f5-e5)
16.gxh8=Q  Sg6 (e5-f6-g6, e5-f5-g6)
17.Qd4

Or 17.Sxg5 (e1-g3-g5) Sxh8 (g6-g7-h8) 18.c4 b5 19.Bb1 bxc4 20.bxc4 
Qb7 21.Ke2 Qb2+ 22.Kf3 [22.Kxe3? Qe2+ winning the f1-rook since 
23.Kxe2 is not possible because of the h8-sissa would give check by 
h8-e5-e2] e2 23.Re1 Qd2 24.h4? [the g5-sissa protects to the e1-rook 
by g5-g3-e1, but...] Sxh4+! (h8-d4-h4 / h4-g4-f3, h4-g3-f3) 25.Kf2 
Qxg5 with a clear advantage for Black.

17. ...    Bh6
18.Bb1     b6
19.c4      Sd6 (g6-g3-d6)
20.Qf6+    Sxf6 (d6-f8-f6, d6-f4-f6)
21.Rxf6    Bg7
22.Rf3     Bxd5?!
23.cxd5    Qxd5+
24.Sd3 (e1-d2-d3, e1-e2-d3)
24. ...    e2+
25.Kxe2    Qe4+
26.Kf2     Bd4+
27.Kf1     c5??
28.Sf4+ (d3-e3-f4 / f4-f6-d8)

Black resigns

Obviously, after 28. ... Qxf4 29.Rxf4, Black has no nothing to make 
in the game.

                          *  *  *  *  *

White: Carlos Cetina                   Villahermosa, Mexico
Black: Carlos A. Cerino                May 25, 1998


                        +-----------------+
                       8| k q s c b b n r |
                       7| p p p p p p p p |
                       6| . . . . . . . . |
                       5| . . . . . . . . |
                       4| . . . . . . . . |
                       3| . . . . . . . . |
                       2| P P P P P P P P |
                       1| C R B K S B Q N |
                        +-----------------+
                          a b c d e f g h

 1.g3      c6
 2.Bg2     d5
 3.d4      e6
 4.f4      Nf6
 5.Nf2     Qc7
 6.b4      Bd6
 7.a4      Nd7
 8.b5      cxb5
 9.axb5    f6
10.Nd3     Nb6
11.Nc5     Bxc5
12.dxc5    Nc4
13.b6      Qc6
14.Cxa7+   Sxa7 (c8-b8-a7)
15.Ra1     Nxb6
16.cxb6    Cc8
17.Rxa7+   Kb8
18.Be3     Cxa7
19.bxa7+   Ka8
20.Bd4     Bg6
21.Qe3     Rc8
22.Qb3     Be4
23.Bxe4    dxe4
24.Qb6     Qxb6
25.Bxb6    g5?

Preferable 25. ... f5. Of course, Black ought to resign rightnow!

26.Sxe4 (e1-h1-e4, e1-b4-e4)

Menacing to the rook by e4-c6-c8.

26. ...    Rc6
27.Bf2     b6
28.Sxf6 (e4-e5-f6, e4-f5-f6)

Menacing to the rook by f6-c3-c6.

28. ...    Rc7
29.Sxb6+ (f6-b2-b6 / b6-b7-a8)
29. ...    Kxa7
30.Sb5+ (b6-a6-b5, b6-a5-b5, b6-c6-b5, b6-c5-b5 / b5-b6-a7, b5-a6-a7)
30. ...    Ka6
31.Sxc7+ (b5-b6-c7, b5-c6-c7 / c7-b7-a6, c7-b6-a6)
31. ...    Ka5

Unique. The sissa covers b7 (c7-b8-b7, c7-c8-b7, c7-b6-b7, c7-c6-b7) 
and b5 (c7-b6-b5, c7-c6-b5). Of course, it also covers a7 by c7-c5-
a7, moreover of the bishop.

32.c3      Ka4
33.Kc2     gxf4
34.Sa7# (c7-c5-a7, c7-a5-a7 / a7-d7-a4, a7-d4-a4)

The sissa covers a3 (a7-e7-a3), a5 (a7-c7-a5, a7-c5-a5) and b5 (a7-a6-
b5, a7-b6-b5).

                          *  *  *  *  *

White: Carlos A. Cerino                  Villahermosa, Mexico
Black: Carlos Cetina                     May 29, 1998


                       +-----------------+
                      8| b c b s n k r q |
                      7| p p p p p p p p |
                      6| . . . . . . . . |
                      5| . . . . . . . . |
                      4| . . . . . . . . |
                      3| . . . . . . . . |
                      2| P P P P P P P P |
                      1| N C B K R S B Q |
                       +-----------------+
                         a b c d e f g h

 1.b3      b5
 2.f3      a5
 3.h4      Ca6
 4.h5      h6
 5.Cc3     b4
 6.Cc4     d5
 7.Cd4     c5
 8.Cd3     Sd7 (d8-c7-d7)
 9.g4      Nd6
10.Sg3 (f1-f2-g3, f1-g2-g3)
10. ...    g6
11.hxg6    Rxg6
12.Bb2     Qh7
13.Bg2     Bc7
14.Sh5 (g3-h4-h5)

Menacing to the d7-sissa by h5-f5-d7.

14. ...    e6

Obstructing the mentioned path.

15.e4      d4
16.a3      Ne8
17.axb4    axb4
18.c3      bxc3
19.dxc3    Nf6
20.Sh4 (h5-g5-h4)
20. ...    e5
21.f4      Nxg4
22.cxd4    exd4
23.f5      Rg5
24.b4      Sd6 (d7-e7-d6, d7-e6-d6, d7-c6-d6)

Menacing to the d3-chancellor by d6-g3-d3.

25.e5

Obstructing the mentioned path.

25. ...    Sxf5+ (d6-e6-f5 / f5-f3-d1)
26.Kc1     Bxg2
27.Qxg2    Se7 (f5-f6-e7, f5-e6-e7)
28.Cxc5??

Better 28.Sf3+ (h4-g3-f3 / f3-a8-f8) Kg8 29.Sxh7 (f3-f5-h7) Kxh7 
30.bxc5

28. ...    Ca2+
29.Kd1     Qb1+
30.Cc1     Sf5+ (e7-e6-f5, e7-f6-f5 /f5-f3-d1, f5-d3-d1)
31.Kd2     Cxb2+
32.Cc2     Qxe1+
33.Kxe1    Cd3+
34.Kf1

If 34.Ke2, then 34. ... Sf4+ (f5-e4-f4 / f4-f3-e2, f4-e3-e2) 35.Sxf4 
(h4-f2-f4, h4-h2-f4) Cxf4+ 36.Ke1 [36.Kd1 Ne3+ 37.Cxe3 Rxg2] Rxe5+ 
37.Kd1 Cd3+ 38.Cd2 Ne3+ 39.Ke2 Cf4+ 40.Ke1 Nxg2+ 41.Kd1 Re1+ 42.Kc2 
Ne3+ 43.Kb2 Nc4+ 44.Cxc4 Cd3+ 45.Kc2 Cc1+ etc.

34. ...    Ne3+
35.Cxe3    Cxe3+
36.Kg1     Cf1#
Written by Carlos Cetina; parts added by Hans Bodlaender.
WWW page created: June 3, 1998. Last modified: March 9, 1999.