# The Mushroom:fbNfsLbF

## A Useful New Piece

The Mushroom is a useful new piece whose characteristics are very much like the Knight, and whose value is as close to that of the Knight as possible.

It is not a particularly strange or exciting piece, but in the context of Chess With Different Armies, it is useful to have another piece that can be substituted for the N or for the fbNF, WA, or WD: it is a different Knight, and multiplies the possibilities of all other chess variants. (Or, of course, the Mushroom might be used as the starting point for a new army. Especially since the zF4 seems to be a perfect Bishop-substitute.)

## How the Mushroom Moves

The Mushroom moves like a narrow Knight, or forward as a wide Long Knight, or to the rear as a Ferz. In my funny notation (which is becoming widely used despite its flaws), this would be fbNfsLbF, quite a mouthful.

``` . . . . . . . .
. . . . . . . .
. . . 1 . 1 . .
. 1 . . . . . 1
. . . . 0 . . .
. . . 1 . 1 . .
. . . 1 . 1 . .
. . . . . . . .
```
The ugly ascii diagram shows how a White Mushroom on e4 could jump to d6, f6, b5, h5, d3, f3, d2, or f2; jumping over obstacles like a FIDE Knight. Can you see the mushroom in the diagram?

## Characteristics of the Mushroom

Half of its moves change color, half stay on the same color of square; some of its moves are longer than a Knight, and some are shorter.

The Mushroom needs 4 moves to reach the square directly behind it or the two squares an Alfil-jump forward from it (the Knight needs 4 moves to reach any of the 4 Alfil-jump squares).

Nobody has ever constructed a Mushroom Tour, that is, a sequence of 64 moves where a Mushroom lands on each square once and then returns to its starting point.

The Mushroom can defend a Pawn that defends it.

The endgame "King plus two Mushrooms versus King" should be a forced mate. It is possible to construct a mating position with King and Mushroom versus King, but of course this checkmate cannot be forced:

``` . . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . M .  -- the Mushroom's previous position did not attack
. . . . . K . .     h3, so black did not need to allow checkmate.
. . . . . . . k
```

## Concrete Example

Suppose both sides have the usual FIDE army, but White has Mushrooms instead of Knights.

After 1. e4 e5 2. (fbNfsLbF)g1-f3, the Mushroom attacks e5, as a Knight would, but does not attack d4 (instead, it defends the Bishop that might soon be at c4). In addition, it defends g2 but does not defend h2 (similarly e2 and d2); and instead of being able to go to h4, it has no move in that direction. Right now, the Mushroom is slightly less effective than a Knight would be.

Following up with 2...Nb8-c6 3. (fbNfsLbF)b1-c3 Ng8-f6, we see that e4 is undefended, which seems to be a problem.

Onr logical course of action is to defend e4 with 4.(fbNfsLbF)c3-d5, when Black might trade off all the Knights and Mushrooms with 4...Nf6:d5 and 5...e5-e4 (White could win a Pawn, but I seem to remember that Black's development is adequate compensation -- the exact same position can be reached in FIDE Chess with the same move order).

In the King's gambit, after 1. e4 e5 2. f4 ef 3. (fbNfsLbF)f3 g5 4. h4 g4 5. (fbNfsLbF)g5, the fact that the (fbNfsLbF) at g5 attacks the Pawn at f4 is significant, and favors White.

In the Closed Variation of the Ruy Lopez, after 1. e4 e5 2. (fbNfsLbF)f3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 O-O 8. c3 d6 9. (fbNfsLbF)b1-e2 is an interesting possibility. If 9...Bg4 10. (fbNfsLbF)e2-f1 should be good. (Just as in FIDE Chess, 9...N:e4 loses to 10.Bb3-d5; if Black had a Mushroom at f6, things would be different.)

It seems that the Mushroom is especially interesting because it is such a small change from the Knight...

## Mushroom Soup

Just as there is a piece called the Chancellor, which combines the powers of the Rook and the Knight, so must there also be a piece called the Champignon, combining Rook and Mushroom.

In order to have a Mushroom Queen, like the Amazon Queen, you'd have to use a move such as (fbNsLQ); similarly, the archbishop (bishop plus Knight) could be replaced with (fbNsLB).

And, of course, Augmented Mushrooms (AfbNsLbF, DfbNsLbF, WfbNsLbF) would be fair replacements for Augmented Knights (NA, ND, NW, NF).

## Mushrooms and Crabs and Toadstools

Compare the Mushroom to a Crab with the same two powers added:

``` . . . . . . . .
. . . . . . . .
. . . 1 . 1 . .
. 1 . . . . . 1
. . . . 0 . . .
. . 1 1 . 1 1 .
. . . . . . . .
. . . . . . . .
```
(Looks more like a butterfly.) This piece might be a bit stronger than a Mushroom in the general case.

## Random Pieces

The Mushroom and the Crab are the result of careful selection, but it is also possible to find new pieces by purely mechanical means.

Here are three diagrams:

``` . . . . . . . .      . . . . . . . .       . . . . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
. . . 1 . 1 . .      . . . 1 . 1 . .       . . . 1 . 1 . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
. . . . A . . .      . . . . B	. . .       . . . . C . . .
. . . . . . . .      . . . . 1 . . .       . . 1 . . . 1 .
. . . 1 . 1 . .      . . . . . . . .       . . . . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
```
Piece A is the fbN, and if you will look closely you can see that it is only capable of visiting 25% of all the squares on the board. This weakness makes the fbN much weaker than half a Knight. By itself, the fbN is not a good piece.

Piece B is a very interesting new idea, which is even weaker than a Crab, but can visit all squares of the board. It is worth more than a Pawn, almost half a Knight. The fNbW is so interesting it deserves to have a name, and it deserves to be used in some games.

Piece C is the Crab, which can visit all the squares, is worth about half a Knight, and makes only Knight moves. It is a very special piece.

A Wazir should be worth about half a Knight; if we add the power of a Wazir to each of the above half-Knights, we get:

``` . . . . . . . .      . . . . . . . .       . . . . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
. . . 1 . 1 . .      . . . 1 . 1 . .       . . . 1 . 1 . .
. . . . 1 . . .      . . . . 1 . . .       . . . . 1 . . .
. . . 1 D 1 . .      . . . 1 E	1 . .       . . . 1 F 1 . .
. . . . 1 . . .      . . . . 1 . . .       . . 1 . 1 . 1 .
. . . 1 . 1 . .      . . . . . . . .       . . . . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
```
Piece D is the fbNW, which was mentioned in the introduction to the Fibnif. It should be a very interesting piece and just as strong as a Knight, but little attention has been paid to it.

Piece E is new, and should be nearly as strong as a Knight until the endgame. (Hans has suggested that the priority I give to forward moves because "we start the game with the foe in front" is situational. This makes sense to me.)

Piece F is a Crab plus Wazir (a new piece), and might be even stronger than a Knight -- I like it, anyway. The W move works very well with this, especially when you consider that the square directly in front of itself is one of the hardest squares for the Crab to reach (it takes 5 moves); the W adds great flexibility, compensating for the weakness of the Crab, and the Crab adds distance, compensating for the weakness of the W.

``` . . . . . . . .      . . . . . . . .       . . . . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
. . . 1 . 1 . .      . . . 1 . 1 . .       . . . 1 . 1 . .
. . . 1 . 1 . .      . . . 1 . 1 . .       . . . 1 . 1 . .
. . . . G . . .      . . . . H	. . .       . . . . I . . .
. . . 1 . 1 . .      . . . 1 1 1 . .       . . 1 1 . 1 1 .
. . . 1 . 1 . .      . . . . . . . .       . . . . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
```
Piece G is the Fibnif, which is well-known, well-tested, and is an excellent "Knight".

Piece H is new, must be a bit weaker than the fbNF, but should be almost as strong as the fbNF. Its flexible retreat is interesting.

Piece I is Crab plus Ferz, flexible and strong (as strong as piece F, above, anyway). It's "just another Knight", and there are already so many good Knights; I should put up a page on "Chess with Different Knights", for conservative chessplayers who are afraid to try chess variants. (For some reason, I like the Crab + Wazir better than the Crab plus Ferz.)

Adding a Dabaaba or an Alfil to an fbN would produce an awkward and colorbound piece; adding A or D to the other two would produce pieces that are okay, good but not exciting. "Just another Knight".

Instead, here are a few interesting half-Knights:

``` . . . . . . . .      . . . . . . . .       . . . . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
. . . 1 . 1 . .      . . . 1 . . . .       . . . 1 . . . .
. . . . . . . .      . . . . . 1 . .       . . . . . 1 . .
. . . . J . . .      . . . . K . . .       . . . . L . . .
. . . 1 . 1 . .      . . . . 1 . . .       . . . . . . 1 .
. . . . . . . .      . . . . . . . .       . . 1 . . . . .
. . . . . . . .      . . . . . . . .       . . . . . . . .
```
Piece J is an fNbF, a Crab with a short wheelbase. Although it is more flexible, I think it might be weaker than a Crab because it has less ability at getting from side to side. It deserves a try.

Adding a Wazir to the fNbF produces an interesting result.

Piece K and piece L are asymmetrical, they move differently to the left and to the right. Presumably, if you had a pair of these in a game, you'd have one left-handed piece and one right-handed piece.

I think that right-handed/left-handed pieces would be confusing to use in a game; however, piece K (flNfrFbW) seems very interesting.

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