Raumschach is the classic 3D Chess.
Flatschach is a tongue-in-cheek exploration of what a two-dimensional version of Raumschach might be like. Take the 5 5x5 boards of Raumschach, place them side by side to form a 5x25 board, give each piece the movement capabilities that it would have on the center cell of the 3D board, and you have Flatschach.
As stated, pieces in Flatschach move as they would if they occupied the center cell in Raumschach.
- Pawns move 1 forward, as in Chess, or leap 5 forward. They capture as pawns or as (1,6) leapers.
- Kings move as Chess kings or as leapers: (0,4), (0,5), (0,6), (1,4), (1,5), (1,6).
- Rooks move as short rooks (R2) or as (0,5) leaper-riders.
- Bishops move as short bishops (B2), as (0,6) leapers, or as (0,4) and (1,5) leaper-riders.
- Knights move as Chess knights or as (0,3), (0,7), (0,9), (0,11), (1,10), or (2,5) leapers.
- Unicorns move as (1,4) or (1,6) leaper-riders.
- Queens move as Rooks, Bishops, or Unicorns.
Raumschach has flaws. Many think the Unicorn is too weak and the King is too mobile. I think the diagrams above illustrate why.