Emperor's Nobility 3d Latrunculi (EN3dL)

Up-for-Deletion Variants
This is a not very Chess-like 3d variant with a complex chain of promotions. I would therefore be interested to know whether other CVP members agree that this variant should be dropped.

Setup

Pieces

Array pieces:
The EMPEROR can move one step in all 26 directions, and must be kept out of Check.
The HEIR can move one step in the 4 forward Bishop directions and the 4 forward Unicorn directions.
The ROOK moves any distance through empty intermediate cells in the six obvious directions.

First stage of promotion:
The BARON can move one step in the 12 Bishop directions and the 8 Unicorn directions. It results from promoting an Heir.
The BARONESS is the compound of the Rook and Baron. It results from promoting a Rook.

Second stage of promotion:
The COUNT can move one step in the forward Rook direction and the 4 forward Unicorn directions. It results from promoting a Baron.
The COUNTESS can move any distance through empty intermediate cells in the same 5 directions. It results from promoting a Rook or Baroness.

Third stage of promotion:
The DUKE can move one step in the 6 Rook directions and the 8 Unicorn directions. It results from promoting a Count.
The DUCHESS can move any distance through empty intermediate cells in the same 14 directions. It results from promoting a Countess.

Fourth stage of promotion:
The PRINCE can move one step in the 6 Rook directions and the 12 Bishop directions. It results from promoting a Duke.
The PRINCESS can move any distance through empty intermediate cells in the forward Rook direction and the 4 forward Bishop directions. It results from promoting a Duchess.

Fifth ad final stage of promotion:
The ARCHDUKE can move one step in all 26 directions, but is capturable. It results from promoting a Prince.
The EMPRESS can move any distance through empty intermediate cells in all 26 directions. It results from promoting any long-range piece.

Rules

Each piece has a specific promotion rank, on reaching which it undergoes direct promotion (DP). This promotion also triggers an indirect promotion (IP) of piece of another kind, if the player still has at least one piece of that latter kind. If there is more than one, only one can be chosen for indirect promotion. It must be the foremost or an equal foremost in the case of an enemy-camp promotion, or the hindmost or an equal hindmost in the case of an own-camp promotion. Where there is a choice of multiple kinds of piece for IP the foremost/hindmost restriction applies across all suitable pieces. Both DP and IP are always required where possible. The promotions are as follows:

Check, Checkmate, and Stalemate are as usual. A player can also win by marriage, as in Doug Chatham's Bachelor Chess. This involves a move ending with the Emperor and an Empress, both of their own army, adjacent on any radial and not in Check. In a tournament or other series of games, it is advisable to value a win by marriage as worth at least three wins by Checkmate, to encourage what may otherwise be neglected as a harder win.

Notes

Originally I considered a few more stages of promotion, but stripped some out. The pieces that I excluded were those which least matched up in terms of name. Thus as it would be illogical to have Kings sprouting up I omitted Queens as well, as Princeling suggested a juvenile I dropped that as well. This is the reason of the odd pairing of the symmetric Prince and asymmetric Princess at the fourth stage. The basis for the names is fully explained in my article Man and Beast 01: Constitutional Characters.

"Promoting" a symmetric piece to a forward-only one may seem like a retrograe step, but the following should be noted.
1: Such promotions, when direct, occur in one's own camp, where there are plenty of subsequent moves. When indirect, the piece is as far back as any of its kind.
2: The promotion from Countess to Duchess brings in the longest-range move of all, along a file.
3: It ultimately results in further promotion to another symmetric type - if the piece is not captured first!
4: As stated in the rules, it is not as if the player has a choice anyway!

Regarding my explicit use of the word Hindmost, see also Ringworld Chess.