Paired Piece Tunnelchess
This variant is part of the Tunnelchess family of 3d variants. As regards radial linepieces its Emperor, Empress, 4 Unicorns, and 2 aside of every other compound compromises between the Simple variant with 4 of each simple piece and 1 of each compound, the Intermediate variant with no simple ones but twice the compounds of this one, and the Pawnless variant with twice everything except Unicorns. As with Simple and Intermediate it concentrates these pieces on the first rank. The second rank is filled with Coheirs (of which more below) in PAIRED-LINEPIECE TUNNELCHESS, with pairs of simple and compound 2:m:n leapers along with curved-path pieces in PAIRED-EVERYTHING TUNNELCHESS, and with pieces changing between the two in ORDERS-OF-KNIGHTHOOD TUNNELCHESS. I considered adding these to the main Tunnelchess page but eventually decided against this. Reasons include:1 losing the link between Tunnel/Wall/Frame files of the Tunnelchess board and central/intermediate/edge files of the FIDE board as carrying every-radial compounds/minor pieces/Rooks;
2 the multiplicity of subvariants;
3 PLTC's distinctive second-rank pieces and PETC's distinctive compound 2:m:n leapers, which are not found on the standard Tunnelchess page but are found together in Ecutunnel and Ecumillstone and now also in Nichtschach;
4 the backlog of posting by editors at the time of invention.
Setup
Files are lettered a-d on the top level, e-h on the next, i-l on the next, and m-p on the bottom one. The Frame comprises files a/d/m/p, the Wall b/c/e/h/i/l/n/o, and the Tunnel f/g/j/k. Ranks are 4x4 supersquares of cells, numbered from 1 at the White end to 8 at the Black end.PAIRED-EVERYTHING TUNNELCHESS
PAIRED-LINEPIECE TUNNELCHESS differs in having a Coheir on every cell of ranks 2 and 7. ORDERS-OF-KNIGHTHOOD TUNNELCHESS replaces these with Garters on the Frame and Tunnel, Thistles in front of the Duchesses and Governors, and Patricians in front of the Bishops and Rooks.
Pieces
First rank| Simple radial linepieces | |
 | The ROOK moves any distance through empty intermediate cells in the 6 orthogonal directions, each of which is the intersection of 2 2d planes and at right angles to the other plane. It is unbound. |
 | The BISHOP moves any distance through empty intermediate cells in the 12 standard diagonal directions, each of which is a diagonal of a 2d plane and at 45° to the other 2 planes. Each Bishop is bound to half the board. |
 | The UNICORN moves any distance through empty intermediate cells in the 8 nonstandard diagonal directions, commonly called triagonal, which are all at 35° to all three planes. Each Unicorn is bound to a quarter of the board, which is why there are four of them aside. |
| Compound radial linepieces | |
 | The EMPEROR moves one step in any of the 26 radial directions. It is unbound, but must be kept out of Check. |
 | The EMPRESS is the compound of Rook, Bishop, and Unicorn. It inherits the Rook's lack of binding. |
 | The QUEEN is the compound of Rook and Bishop. It inherits the Rook's lack of binding. |
 | The DUCHESS is the compound of Rook and Unicorn. It inherits the Rook's lack of binding. |
 | The GOVERNOR is the compound of Bishop and Unicorn. The components' independent bindings make the piece unbound. |
| In PETC, simple 2:m:n leapers | |
 | The KNIGHT makes any 2:1:0 leap. The zero smallest coordinate indicates that it always moves within one of the three planes, and the single odd coordinate that it is unbound and colourswitching. |
 | The SEXTON makes any 2:1:1 leap. The nonzero smallest coordinate indicates that it never moves within one of the three planes, the 2 odd coordinates that it has the Bishop's binding, and the largest coordinate being the sum of the others that it can triangulate. The name puns on its Square of Leap Length being 6. |
 | The NINJA makes any 2:2:1 leap. The nonzero smallest coordinate indicates that it never moves within one of the three planes, and the single odd coordinate that it is unbound and colourswitching. The name puns on its Square of Leap Length being 9. |
| In PETC, compound 2:m:n leapers | |
 | The CHURCHWARDEN is the compound of Knight and Sexton. Sextons start on Wall files e and h, beside the Empress and Emperor respectively. The name means a higher ecclesiastical lay rank than Sexton. |
 | The SAMURAI is the compound of Knight and Ninja. Samurais start on Wall files b and c, directly above the Empress and Emperor respectively. The name means a Japanese warrior of higher rank than a Ninja. |
 | The OBERON is the compound of Ninja and Sexton. Oberons start on Frame files a and d, diagonally adjacent to the Empress and Emperor respectively. The name, that of a Shakespeare character, is used here to stand for Oblique baron, from the SOLLS of its components being in a ratio of 2:3 like the radial Baron. |
| In PETC, Curved radial linepieces | |
 | The CURVED DOUBLE RHINO (Rhino for short in this variant) makes up to 6 steps, alternating between orthogonals and standard diagonals, through empty intermediate cells with a 45° turn at each forming sides of an octagon. It can start with either and end with either. If the a2 Rhino is the first piece moved it can follow the paths a2-a3-b4-c4-d3, a2-a3-e4-i4-m3, a2-b3-b4-a5, a2-b3-c3, a2-e3-e4-a5, or a2-e3-i3. If the b2, e2, or f2 leaper is moved before it this opens up further paths. In 2d this piece appears in John Savard's Leaping Bat Chess. |
 | The APOSTLE is a Curved Bishop making up to 4 steps along standard diagonals, through empty intermediate cells with a 60° turn at each forming sides of a hexagon. If the m2 Apostle is the first piece moved it can follow the paths m2-i3-f2, m2-i3-j4-o4, m2-n3-j4-e4, and m2-n3-k3. If the j2 Churchwarden is moved first, this opens up the paths m2-j2-f3-e4 and m2-j2-k3-o4. The Apostle shares the Bishop's binding and takes it name from being intermediate between the Bishop itself and the RABBI, the 60° Curved hex-diagonal rider. |
The COHEIR is a restricted version of the Heir, which is the forward-only form of the Baron and moves one step forward (away from its own camp) Bishopwise or Unicornwise. Whereas the Heir need only switch to a different file when it moves, the Coheir must switch to a differnt kind of file. It cannot switch between two Tunnel or two Wall files. Thus the b2 (White) Coheir can make its first move to a3, f3, or g3, but not c3 or e3; the f5 (Black) Coheir can move to a4, b4, c4, e4, or i4 but not g4, j4, or k4. This is a compromise between the full Heir and a divergent piece, and specific to Tunnelchess geometry. If the idea is popular I may make it the standard Tunnelchess front-rank piece.
In OOKTC, file-dependent movers
The GARTER moves as a Coheir except from the Wall files, taken to represent England (at the ends of a cross of files), whence it moves as a Knight. Named after England's order of Knights of the Garter.
The THISTLE moves as a Coheir except from the Frame files, taken to represent Scotland (at the ends of a saltire of files), whence it moves as a Knight. Named after Scotland's order of Knights of the Thistle.
The PATRICIAN moves as a Coheir except from the Tunnel files, taken to represent pre-WW1 Ireland (where the rulers can keep an eye on them ready for post-WW1!), whence it moves as a Knight. Named after (then all of, now just Northern) Ireland's order of Knights of Saint Patrick.
Rules
There is no initial double-step move, En Passant, or Castling.In PLTC, Coheirs may be promoted to a stronger capturable array piece on reaching the enemy Coheir rank and must be should they reach the rank beyond. PETC has no promotion. In OOKTC the second rank pieces are promoted on reaching either rank of the enemy camp, optionally if they have another unpromoted move thence and automatically if not. Garter promotion is to Queen on Wall files, Rook on Frame files, and Bishop on Tunnel files. Thistle promotion is to Duchess on Frame files, Rook on Wall files, and Unicorn on Tunnel files. Patrician promotion is to Governor on Tunnel files, Bishop on Wall files, and Unicorn on Frame files.
Check, Checkmate, and Stalemate are as in FIDE Chess.
This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.
By Charles Gilman.
Web page created: 2006-05-31. Web page last updated: 2016-04-08