Mini four player chess

Variant for 4 players, played on board, smaller than board of standart chess (can be played on standart board by covering or ignoring non-used squares).

Setup

Here is my original setup, but it's good only for team game, where teammates faces each other.

  NBKR
  PPPP
RP----PR
KP----PK
BP----PB
NP----PN
  PPPP
  NBKR

Alternative setup, for all-against-all games and team games, where teammates sits at right angles (for games, where teammates faces each other it can be used to):

  NBKR
  PPPP
NP----PR
BP----PK
KP----PB
RP----PN
  PPPP
  RKBN

Rules

It's not allowed to move pieces from first 2 ranks of one of players to first 2 ranks of player, wich sits at right angles (this rule prevents pawns and knights from capturing pawns on first moves). No castling. Double step is usual. Pawns promotes anywhere on last rank or on 6th rank on files 1, 2, 7, 8 (ranks and files are numbered from pawn's owner's point of view, of course). It promotes to rook, knight or bishop (if you want to allow them promote to queens, it should be stated before playing).
Check, checkmate, stalemate rules may be taken from any other 4-players variants. One of the simpliest variants: capture hostile kings, pieces of captured king changes sides.

Notes