Sovereign S
One step in any of the 26 directions — 26 cells from the centre. It may never move into attack, it is never actually captured, and the two Sovereigns may never become adjacent. With 26 escape squares, trapping one is genuinely hard.
How to play
Oblique is played on a 5×5×5 lattice of 125 cells. It is one continuous three-dimensional field, not five chessboards standing in a row — and almost everything that feels strange about it follows from that one fact.
Coordinates
Every cell has three: a file a–e
across, a rank 1–5 away from you, and a
level A–E upward. A cell is written
level, file, rank, in that order.
Aa1— bottom level, near corner.Cc3— the exact centre of the lattice.Ee5— top level, far corner.
White advances toward increasing rank; Black toward decreasing rank. Levels have no direction of their own: up is not forward for anybody.
How pieces move
Movement is written as direction vectors. A slider repeats its vector until it reaches a wall, a friendly piece, or an enemy piece — which it may capture, ending the ray there. A leaper makes one exact vector and ignores whatever it passes over.
Each figure below shows that piece standing at the centre of the lattice with a line drawn along every direction it has, out to the cell it reaches. The lines and the counts are generated from the same tables the engine moves by, so nothing here can drift away from the game.
Regent R
A slider on all 26 rays: axes, two-axis diagonals and body diagonals alike — 26 cells from the centre. It is the piece that finishes games, and the one the variant rules argue about.
Tower T
A slider on the six axes — along a file, along a rank, and straight up or down through the levels. That last one is the move newcomers forget exists.
Bishop B
A slider on the twelve two-axis diagonals: every move changes exactly two coordinates and preserves the third. It can climb — but only while moving sideways at the same time.
Lancer L
A slider on the eight body diagonals: every move changes all three
coordinates at once. Aa1–Bb2–Cc3–Dd4–Ee5 is a single ray from
one corner of the lattice to the opposite one.
Sentinel N
A leaper on the 24 signed permutations of (2,1,0) — the knight's idea, given a third axis. It jumps over anything in the way and reaches 24 cells from the centre.
Pawn P
Advances one cell forward, and only forward, into an empty cell. The figure shows its captures, which are different vectors: two sideways-forward, and two that go forward while changing level. Four attacked cells, never the one ahead.
A pawn's moves and its attacks are different sets. It can be blocked by a piece it could never capture, and it attacks a cell it can never move to. This is the rule most worth internalising early.
The starting position
Each side has twenty pieces: a Sovereign, a Regent, two Towers, two Bishops, two Lancers, two Sentinels and ten Pawns. White occupies three levels — Bishops and a Lancer on level B, the whole main rank on level C, the Regent and the second Lancer on level D — with pawns on the rank in front of each.
Black is the point reflection of White through the centre of the lattice, so the
files flip too: the Black Sovereign starts on Cc5, but the Black
Regent starts on Bd5 rather than Dd5.
Winning, drawing, and the rest
- White moves first, turns alternate, and moving is mandatory.
- A move may never leave your own Sovereign attacked.
- Check is the Sovereign under attack; checkmate is check with no legal answer, and ends the game. Stalemate — no legal move, but no check — is a draw.
- Other draws: agreement, threefold repetition of the position, and 100 half-moves without a pawn move or a capture.
- A pawn reaching the far rank promotes to a Regent, Tower, Bishop, Lancer or Sentinel. Never a Sovereign.
- There is no castling, no en passant, and no two-cell first pawn move. In a lattice this open they would each cause more trouble than they solve.
Reading a move
Moves are written in long form, with the piece letter first —
S R T B L N P, where N is the Sentinel.
TCa1-Ca4— a Tower moves, taking nothing.RCb1xCc2+— a Regent captures, giving check.PBa4-Ba5=R— a pawn promotes to a Regent.NCc3-Ec4— a Sentinel leaps two levels and a rank.