Symmetric Unirexal Chess

Setup

Set up is FIDE chess. The king is only a half-piece though. The other pieces is full-pieces.

Rules

Each square can contain a half-piece or a full-piece. Containing two different half-pieces (of different kind or color) is not allowed, and more than one full-piece is also not allowed. A half-piece and a full-piece cannot be contained in the same square.

No check/mate. Win by opponent has no king (not even half). Having no legal move, results in a draw.

On your turn, you first optionally make transformation move (see below), and then you must make two half-moves (or you can just make one normal full-move).

A full-move is made by a full-piece, and can capture an opponent's full-piece but not half-pieces (although full-pieces can be made such capture using half-pieces).

A half-move is made by one half-piece, including a full-piece being split. Such move can capture a half-piece but not full-piece. Moving into another same half-piece is OK, to make the full-piece. Passing through a half-piece is not allowed, but it can move there and then move again as your second half-move.

The two half-moves can be made by the same or by two different pieces. They count sequential so one half-piece may unblock another to move on the same turn.

Castling is allowed a half-king and half-rook in their initial positions, regardless of check, regardless of what is in between, regardless if they have already been moved or not. But, it is necessary for the space it lands on, to be legal for those pieces to stand there (so, it may contain the matching half or vacant).

A half-pawn can promote into a half-king if you have only one half-king on your board so far.

Transformation move: If you have one full-piece attacking an opponent's half piece, as your transformation move you may change that one into your color. If your full-piece attacking is pawn and you have only one half-king, you can optionally change opponent's piece into your half-king, instead.