Quite a few games specify that a single piece may move according to different rules according to its situation. Greener Chess is one recent example.
There may have been games, other than Turning Chess, where the rules for a particular piece changed at every move.
Having the change affect all pieces seems to be a new idea. Because this idea creates interesting and distinctive tactical possibilities, I think I would have remembered any game where this happened.
Before the start of the game, an ordered list of powers is chosen for each type of piece.
When a piece moves or captures, it and all other pieces of the same type change their movement/capture powers to the next entry on the list; and after the last entry comes the first entry again.
Castling is a King move. Pawn promotion is a Pawn move.
A long list for every piece type will make the game confusing to play. A long list for Queens combined with a short list for the other pieces would probably be playable; each player has only one exemplar of the Queen piece type, which should make the long list easier to cope with.
The powers on a given list need not be equal, nor nearly even so. For example, a Bishop that changes to Wazir and then back to Bishop would be interesting. Remember, both players have the same army, and both players are affected by the changes, so the game remains equal even if individual pieces fluctuate wildly in strength.
However, Polypiece Chess seems to me to be a rare example of a game which ought to be played without different armies. Having different armies adds complexity in a second dimension; if you want to add complexity, it seems cleaner to do so by using longer lists.
This is a very simple list of powers, but I think both that it produces interesting play and that its simplicity makes it a good introduction to Polypiece Chess.
|Knight (N)||Woody Rook (WD)|
|Bishop (B)||Short Rook (R4)|
|Rook (R)||Nightrider (NN)|
|Queen (Q)||Squirrel + Wazir (WAND)|
Here is how to read the list: the Knight changes to WD when one moves, but then when a WD moves it changes back to a Knight; the Bishop changes to R4 (a short Rook which can move no further than from a1 to e1) and back; the Rook changes to Knightrider and back; and the Queen changes to Wazir plus Alfil plus Knight plus Dabaaba and back. King and Pawn do not change.
The Knight on f3 is now a WD on f3, and does not attack the Pawn on e5. On the other hand, 2...WDg8-g6=N? allows 3. Nf3xe5=WD and the Knight on g6 also becomes a WD, which cannot recapture on e5. What's worse, the usual 3...Qd7-e7 cannot be played.
Defends e5 and impedes White's development because R4 is an awkward piece to have on f1 and c1.
White attacks both e5 and c5, and the R4 cannot move without undefending e5. In retrospect, 3. b2-b4 should be much stronger.
3... Nb8-c6=WD! Black's move changes White's pieces, and so defends against the threats in a way that can be seen nowhere else but in Polypiece Chess.
White renews the threat against c5, and also threatens g7.
4...Qd8-f6=WAND 5. Nb3xc5=WD WDc6xc5=N 6. d2-d3
With 6. b2-b4?, White could hope to win a piece because if the Nc5 moves away, the Nf5 becomes a WD and takes the Queen. However, 6. b4? WANDe4+=Q 7. Ne3=WD Qe4xg2=WAND+ and so on.
The alternative 6. Nf5xg7+=WD Kf8 7. WDg7-g5 Nc5xe4=WD is better, but still not very good for White.
Therefore, the quiet 6. d2-d3, renewing both threats.
6... WANDf6-g6=Q! 7. Nf5-g3=WD O-O
The terrible threat of Qg6xg2=WAND, with check, forced the humble retreat (g2-g3 makes such a weakness!), and now I think Black has at least an equal game.
In FIDE Chess, White wins whoever moves, for example 1. Nd5 Kd8 (other K moves allow Kxa8) 2. Nb6 Nc7 3. Kc6; but in Polypiece Chess, 1. Nd5=WD+ Kd8 and Black threatens WDa8xa7+, so things are different.
In Polypiece Chess, Black to play draws by 1... Na8-c7=WD+ or White to play wins by 1. Kb7xa8 Kc7 2. Na4=WD 3. WDa5=N 4. Nc6=WD.
In Polypiece Chess, and using my example list of powers, White's Knight may not move because doing so puts himself in check when the Nb5 becomes a WDb5. There is nothing better than 1. a6-a7 Nxa7=WD+ 2. Kxa7, and is this a draw?
If White can confine the Black K to a corner, there is a mating position: WKg6, WNe6, BKg8, 1...Kg8-h8 2. Ne6-f8=WD checkmate.
What it it's White's move? 1. Ne6-d8=WD keeps the K confined, but how can you win? The Black K moving will always have made an even number of moves when it gets to g8, and so the only way to win is to make three King moves: 1. Ne6-d8=WD Kh8 2. WDd8-d6=N Kg8 3. Nd6-f7=WD Kh8 4. Kg6-g5 Kg8 5. Kg5-f6 Kh8 6. Kf6-g6 Kg8 7. WDf7-d7=N Kh8 8. Nd7-f8=WD checkmate.
Can W confine the enemy King to a corner? Unfortunately, the answer appears to be "Yes" (although it isn't easy; but it is no harder than K+N+B versus K in FIDE Chess). I say "unfortunately" because this means that the endgame N+P versus N is much simpler in Polypiece Chess with my example list than it is in FIDE Chess.
Perhaps the N should alternate with AD (Alfil plus Dabbabah) instead of with WD, and the Bishop should alternate with -- what? fbNW puts too many Knightly atoms in the game. Perhaps Ferz plus Langskipet? The Langskip is a bit Knightly, but not too much so perhaps. (The Langskip is a long Barc: it makes the (1,3) jumping move, wide forwards and narrow rearwards. For example, a White Langskip on e4 could go to b5, h5, d1, or f1. The funny notation is fsLbbL.)
It doesn't matter. My example list need not be perfect. It demonstrates the basic idea of Polypiece Chess quite well as it is.
This sort of defense seems to render most classical mating attacks unprofitable. This is a defect, not in the game of Polypiece Chess, but in my example list of powers. Apparently the idea of making the moves as different as possible has problems; however, the strangely different tactics may compensate for this defect.
In Atomic Polypiece Chess, when a fbNW makes a W move, the W atom changes value in all pieces that use that atom. Defect: there is no way to become a Rook. Even so, it would be an interesting game.
In Phased Polypiece Chess, using my example power list, W would start with N and Black would start with WD, and 1. Ng1-f3=WD would change the WD at g8 to a Knight.