Inside-out Chess

As a gift for Hans Bodlaender's 44th birthday, his brother Maarten Bodlaender made a chess variant, and a java program that plays the variant. The Dutch name for Inside chess is Binnenste buitenschaak.

Board and setup

Inside chess starting screen. Click to enlarge

The board is 6 by 6 squares. Eight of the squares, namely c3, c4, d3, d4, e3, e4, f3, and f4, have an inner square, i.e., there is a second square, inside the square. This makes the total number of squares exactly 44.

In the setup, each player has six pawns on the second row. Each player has, from left to right: a rook, a knight, a king, a king, a bishop, and a rook. So, each player has two kings; knights are on b1 and e6, and bishops on b6 and e1.

Rules

Chess as normal except:

INNER FIELD RULES

1 If a piece ends at a dual-field, it moves to the inner field, capturing any present enemy as normal (pawn has to capture diagonally).
2 On inner field, only move is a (capturing or non-capturing) move to the outer field.
3 From outer field piece can move as normal, but not back to inner field!
4 Only if both inner&outer field are empty can a bishop, rook pass through a field, otherwise its move must end its move on the inner field.

S-PAWN RULES (multi king rules)

6 There is no 'check' (schaak), kings can be captured as any piece.
7 If a king is captured, on each empty pawn start position of a column.
in which any player has no pawn, a pawn is added to the start position.
8 Pawns promote to kings.
9 If a player loses all kings or cannot move he lost the game.

SIMPLIFICATION :)

10 No castling.
11 No enpassant capture.
12 Not allowed to reverse your own last move.

Some background:

For a while now I wanted to put multiple pieces on a single field, this game doesn't really do that, but get's close.
The 'inner fields' nicely make the board "larger" again, small size is often problematic as long as Hans is young.
The S-PAWN & multiple king rules resulted from a cheap joke, but actually turned into a surprising game mechanic that cost me several testing games. Since only the last king really counts I'm pretty sure my evaluation function is wrong :)
Most other rules, choices of pieces were made to simplify the programming :)
As for inspiration from other games, I usually think about what I'm bored with in chess, in this case the single king.

Written by Maarten Bodlaender. Edited by Hans Bodlaender.

WWW page created: April 27, 2004.