Spirit Explained

Spirit:

Note: The spirit uses the same graphic as the witch, except that it is mirrored to look the other way.

Inventor: @HorribleTomato

Notation: S

Movement:

The spirit can not capture enemy pieces

The spirit moves like a knight

The spirit can 'capture' friendly pieces which results in the spirit 'possessing' that piece.

However, the spirit can not possess a spirit or a piece possessed by another spirit.

The spirit can move to the marked green squares like a knight.

Example 1:

Whites spirit can not capture blacks pawn on c5. However it can capture the pawn on e5 to possess it.

1. Sxe5

Possessed pieces:

A possessed piece gains the ability to move and capture like a knight

Example 2:

Whites bishop is possessed by a spirit. The bishop can move like either a bishop or knight. Black is checkmated.

Example 3:

Whites pawn is possessed by a spirit. The pawn can move like either a pawn or a knight. White plays 1.c8=Q#

The new queen is still possessed by the spirit, so the queen can move like either a queen or a knight. Black is checkmated.

Unpossessing a piece:

A spirit can move away from the piece it is possessing with its normal movement. The piece will no longer be possessed when the spirit moves away from it. The spirit is then able to possess a new piece.

Example 4:

Whites knight is possessed by a spirit. The knight can move like a knight (Since it already can move like a knight it doesn't gain any movement from the spirit). White can play 1.Se5 and leave the knight.

Or, a different option for white was to play 1.Sxe1

Important note: In notation, you should only use the character S when moving the spirit. Do not use that character when moving a possessed piece. There is a big difference between the moves Ne5 and Se5. One is moving the possessed piece, while one is leaving it and only moving the spirit. You may use the notation PN instead of N when moving a possessed knight, but that is optional. PP can be used when moving a Possessed Pawn.

Transparent ability:

A spirit that is not possessing any piece is transparent to allied pieces. For rules on transparency, see the rules for the witch.

Invulnerability:

A spirit that is not possessing any piece can only be captured by possessed pieces.

Fairy piece interactions:

Pieces without any normal capturing moves will not gain capturing knight moves from the spirit. For example, if a spirit possesses a witch, the witch just moves as normal and can not capture.

Summary:

The spirit moves like a knight

The spirit can not capture enemy pieces

The spirit can 'capture' friendly pieces which results in the spirit 'possessing' that piece

The spirit can not possess a spirit or a piece possessed by another spirit

A possessed piece can move like a knight in addition to its normal movement

A spirit can move away from the piece it is possessing with its normal movement

A spirit that is not possessing any piece is transparent to allied pieces

A spirit that is not possessing any piece can only be captured by possessed pieces.

Does a possessed Witch make pieces transparent?

So a Spirit possesses at most one piece at one time?

Yes. Possessing a piece only gives the piece the ability to move like a knight. It doesn't affect anything else, so the witch still has all its other functions when it is possessed.

The spirit is basically inside the piece it possesses and when the possessed piece moves, the spirit moves with it. If the spirit moves away from a piece that piece is no longer possessed. This inherently means that a spirit can only possess one piece at a time.

Thanks Martin0 for the rules. I moded one game with spirit (Ry vs. McGoohan) and can be seen (here).

Before starting the game, we added these addendums:

1) A possessed pawn promotes on the 8th rank as usual, even if it moves there as knight.

2) A pawn may not make a 2-square move if it has made any other move (including moving as a knight while possessed).

3) A possessed king may move as knight even if checked.

I think they're "common-sense" but we added them to make sure there's no disagreements during the game.

Also, I believe Ry used the spirit to possess a pawn, which he was then able to advance quickly, creating pressure of promoting it. Maybe a good game strategy?

Now that I understand the piece better I also like it more. Only more difficult to mod.

Two other questions:

1) Can a piece be possessed by capturing the spirit? (the pieces moves to the spirit, rather than the spirit moving to the piece)?

2) Can a possessed piece move leaving the spirit behind? That means the spirit remains on the square, and the piece moves becoming un-possessed?

(I have my assumed answers, but I'm curious how others interpret these situations)

1) No

2) No

If any of those were possible, it would have to be stated in the rules, but it isn't. The only way for a spirit to possess a piece is for the spirit to capture it. The only way to unpossess a piece is for the spirit to move away from it.

So, if a spirit possesses the king, the king can move like a knight. Doesn't that make him extremely hard to catch?

Yes, the king will indeed become hard to catch. But I'm not sure if it is really a big problem, since it most cases I think the spirit is better to use offensively, rather than defensively. If we get to endgames, then the spirit probably rather possess pawns to promote, rather than possessing the king.

I suggest adding a rule that a spirit can not possess another spirit. Rules for a possessed spirit would be a bit weird. Thoughts?

This question is only relevant when an army has two or more Spirits. If we consider the existing rules so far, a Spirit can possess an allied Spirit, but doing so has no benefit at all. Which is also the case if a Spirit possesses a Knight. So you could choose to leave the rules as they are.

Can a possessed spirit possess another piece?

Can a possessed spirit capture enemy pieces?

Can a possessed possessed spirit possess another piece?

Can a possessed possessed possessed spirit possess another piece?

What happens when a possessed possessed spirit unpossesses a piece? Does it become a possessed spirit or just a spirit?

What would the graphical difference be between a possessed spirit compared to a possessed possessed spirit and possessed possessed possessed spirit and to PPPPS and PPPPPS etc.?

Is there a difference if a possessed spirit possesses a spirit compared to if a spirit possesses a possessed spirit?

Promotions to spirit makes a spirit possessing a spirit possible, even if the game only starts with one allied spirit. This is very different compared to possessing a knight. A knight can capture enemy pieces by moving like a knight, while a spirit can not.

+1. Let's just cross the multiple spirits bridge when we get there

My previous comment is inaccurate because I forgot that a possessed piece gets Knight move and capture.

I think that if you stick to the current rules, nested possession is possible, but it becomes a meaningless mess. I am convinced that the current rules inherently give straightforward answers to all questions posed by Martin0 in #15. But it does not make the piece any better, just a mess.

I see two reasonable options, which lead to minor rule modifications.

1. A Spirit cannot possess a Spirit. Simplest option.
2. A Spirit can possess a Spirit, but further nested possession is not allowed. So a possessed Spirit cannot possess yet another piece, but can capture. With this rule, two Spirits can merge into what is basically a Knight, which can later split again into two Spirits.

Agreed @evert823

We could also add that a possessed piece can not be possessed (so 2 spirits can not possess the same pawn for example).

If we allow a spirit to possess another spirit, then the possessed spirit would still be transparent and can only be captured by possessed pieces, so it is considerable worth more than a knight (This said, 1 spirit is generally considered worth more than a knight, so using 2 spirits this way might not be that impressive).

My main goal with a rule change is to make it simpler and as you say, avoid a mess.