Looking for a chess variant with a circular board I am looking for a certain chess variant played on a circular board.

The variant is played with the usual chess pieces (no fairies involved) on a peculiar circular board. The central part of the board is filled with triangles (alternating black and white) and is part of the playing field. The outer rings are made of only slightly deformed squares. The board was checkered (alternating black and white fields).

A particular feature of the Chess Variant I'm looking for is the movements of the bishop: It changes colour when moving across the centre of the board (a diagonal step is analysed as one step forward followed by one step orthogonally sidewards). Also the Knight has very peculiar moves in the centre of the board.

I remember to have seen a description of this Chess Variant in a German student's newspaper in the 1980s (probably issued by Fachschaft Physik at Ruhr-Universität Bochum). I was not able to retrieve this variant anywhere, it is AFAIK not in the "circular board" category at http://www.chessvariants.org

EDIT: it is a two-player variant (I thought of this as a default and didn't mention it explicitly). The rooks moved either radially or orbiting around the circles.

I'd like to know: Name of the variant, name of the inventor and date of first publication, full ruleset (initial position, exact board and rules).

EDIT2: The number of the triangles in the central disk must be divisible by 4 (it's probably 16) because triangles of the same colour face each other. Another feature of the bishop's movement I remember again now: A bishop crossing the centre can actually choose two different continuations because the diagonal movement can be achieved following two different "staircases" of alternating orthogonal moves.
A few suggestions:

This looks sufficiently circular and weird, though I didn't find the rules.

For three people.

And there is apparently a circular citadel chess, with triangles in the middle.