user17823: Why do pieces move the way they do? Was there any reason behind the decision in the early history of chess?
This Quora post for example mentions (no citations):

Queen can give directions. And she can do, what a King cannot. This is represented by her unlimited range in any direction.

However, in an old form of chess, Shatranj, the queen (fers) could only move one square diagonally, therefore the answer is not accurate.

user27250: Initially, the Shad Yantra game was invented 8000+ years, and was played in Dashpaad or Dashpad.
Dashpaad (10x10) is the board which means 10x10 squares.
Shad Yantra is the name of the game which means 6 Principles or Devices in War. These principles were later cursed as Conspiracy Theory in Indian Sub-Continent.
After the Dashpaad board, the Ashtpaad (8x8) board was evolved with off-track moves and rules. These rules later took the name of new games like Chaturanga and then Modern Chess etc.
In Shad Yantra, Rules were purely based on Categories. These Categories are:
Army: Commandar General or Queen, Officers and Resources.
Immortal: Guru or Peace Ambassador.
Royals: Raaja means King and Deputy of King called Mantri.
Impersonator: Spies, Chaarak or Guptchar.


Army: Within Army, there are 3 level of Officers.

1.a Pawns as common people and not regular soldiers.
Pawns are non autonomous and immovable resource. They are also on 0 level, hence pawns cannot move on their own. They can move only as per the neighboring Senior Rank Officer.
All Officers and Royals are autonomous units. Hence they can move 1 step only. Hence, when Officers are in touch with Army General, or Royal King or Royal Mantri (Deputy of King), or Naarad (Even opponent Naarad), or Impersonator Spy - these officers can move additional steps as per their level. This is called elevated move.

1.b.1 Bishop or Elephant Unit are on 1st level. So bishop gets 1 extra step (2 in total) in any direction when Elevated.
(There was no decimal system during Ramayan period, so we will be using intermediate ranking as .5 which means jumping)
1.b.2 Knight is on Level 1 and intermediate (lets assume 0.5 level). So Knight gets 1 extra step (2 in total when elevated). Intermediate means he can jump as horse (Famous L, I, V shapes). Here Knight cannot jump over opponent.
1.c.1 Rook is on 2.00 level. So elevated Rook gets extra 2 steps (3 in total).
1.c.2 Army General ( which we incorrectly call as Queen) is on 2nd and Intermediate level (lets assume 0.5 level). Elevated Army General gets extra 2 steps (3 steps in total). Intermediate means he can jump as horse (Famous L ,I , V shapes). Here, General cannot jump over opponent.

Immortal: Naarad or Guru or Peace-Maker is on 3rd level. Naarad is always elevated and does not require any assistance. They can move upto 4 steps in total and no help is required.

Royals: Within Royals, there is 1 level of Royal.


3.a.1 Mantri is on same 3rd level like Naarad but more powerful. Elevated Mantri can move 4 steps in total when helped. Otherwise without help, can move 1 step only.
3.a.2 King is on 3rd and intermediate (lets assume 0.5) level. Elevated King can move 4 steps in total when helped. Otherwise without help, can move 1 step only. However, King can also jump like horse because it has intermediate Rank.
King is the most powerful of all pieces, but in modern chess King moves 1 step only.
** Impersonators or Spies can move like any piece**
4.a Default moves of all Spies is 1. When they get elevated or helped, they can move like any piece on board. They can even jump over any piece, like horse. When helped or elevated, they can move secretly, even without breaking borders.
Sources: Agasthya smriti (obsolete) and samhita, Kautilya Arthshastra

user17823: 
The king shouldn't rush into battles, but instead, he should go very slowly to beat his enemies.
The queen (fers) should guard the king and stay in his side. [1]
The bishop (fils) are the elephants the king used to bring. They were moved diagonally to wound the ranks of their enemies. Because no one dared to face them, the fils could leap over intermediate pieces. [2]
Good captains lead the ranks by turning horses to the right and left to guard their men and conquer the enemies.
The rooks (the ranks of the soldiers) go in whichever direction they like and as far as they think is best to conquer their enemies.
The pawns (the army soldiers) can't move too far because they carry their weapons. Some, however, can until they capture because afterward, they cannot do it. And this is like when ordinary people steal some things, that they carry them on their backs.
The soldiers cannot wound an enemy in front of them, so instead, they wound (capture) the ones located diagonally that least expect it.

[1] See Wikipedia on the original movement of the queen.
[2] See Wikipedia on the original movement of the bishop.
Source: this translated version  of Libro de los Juegos ("Book of Games"), pages 8-9.

17823: <p>Why do pieces move the way they do? Was there any reason behind the decision in the early history of chess?</p>
<p><a href="https://www.quora.com/Why-do-pieces-move-in-the-way-they-do-in-chess-Is-it-logical" rel="nofollow noreferrer">This Quora post</a> for example mentions (no citations):</p>
<blockquote>
<p>Queen can give directions. And she can do, what a King cannot. This is represented by her unlimited range in any direction.</p>
</blockquote>
<p>However, in an old form of chess, <a href="https://en.wikipedia.org/wiki/Shatranj" rel="nofollow noreferrer">Shatranj</a>, the queen (<a href="https://en.wikipedia.org/wiki/Ferz" rel="nofollow noreferrer">fers</a>) could only move one square diagonally, therefore the answer is not accurate.</p>
 27250: <p>Initially, the Shad Yantra game was invented 8000+ years, and was played in Dashpaad or Dashpad.</p>
<p>Dashpaad (10x10) is the board which means 10x10 squares.</p>
<p>Shad Yantra is the name of the game which means 6 Principles or Devices in War. These principles were later cursed as Conspiracy Theory in Indian Sub-Continent.</p>
<p>After the Dashpaad board, the Ashtpaad (8x8) board was evolved with off-track moves and rules. These rules later took the name of new games like Chaturanga and then Modern Chess etc.</p>
<p>In Shad Yantra, Rules were purely based on Categories. These Categories are:</p>
<pre><code>Army: Commandar General or Queen, Officers and Resources.
Immortal: Guru or Peace Ambassador.
Royals: Raaja means King and Deputy of King called Mantri.
Impersonator: Spies, Chaarak or Guptchar.
</code></pre>
<ol>
<li>Army: Within Army, there are 3 level of Officers.</li>
</ol>
<p>1.a Pawns as common people and not regular soldiers.</p>
<p>Pawns are non autonomous and immovable resource. They are also on 0 level, hence pawns cannot move on their own. They can move only as per the neighboring Senior Rank Officer.</p>
<pre><code>All Officers and Royals are autonomous units. Hence they can move 1 step only. Hence, when Officers are in touch with Army General, or Royal King or Royal Mantri (Deputy of King), or Naarad (Even opponent Naarad), or Impersonator Spy - these officers can move additional steps as per their level. This is called elevated move.
</code></pre>
<p>1.b.1 Bishop or Elephant Unit are on 1st level. So bishop gets 1 extra step (2 in total) in any direction when Elevated.</p>
<p>(There was no decimal system during Ramayan period, so we will be using intermediate ranking as .5 which means jumping)</p>
<p>1.b.2 Knight is on Level 1 and intermediate (lets assume 0.5 level). So Knight gets 1 extra step (2 in total when elevated). Intermediate means he can jump as horse (Famous L, I, V shapes). Here Knight cannot jump over opponent.</p>
<p>1.c.1 Rook is on 2.00 level. So elevated Rook gets extra 2 steps (3 in total).</p>
<p>1.c.2 Army General ( which we incorrectly call as Queen) is on 2nd and Intermediate level (lets assume 0.5 level). Elevated Army General gets extra 2 steps (3 steps in total). Intermediate means he can jump as horse (Famous L ,I , V shapes). Here, General cannot jump over opponent.</p>
<ol start="2">
<li><p>Immortal: Naarad or Guru or Peace-Maker is on 3rd level. Naarad is always elevated and does not require any assistance. They can move upto 4 steps in total and no help is required.</p>
</li>
<li><p>Royals: Within Royals, there is 1 level of Royal.</p>
</li>
</ol>
<p>3.a.1 Mantri is on same 3rd level like Naarad but more powerful. Elevated Mantri can move 4 steps in total when helped. Otherwise without help, can move 1 step only.</p>
<p>3.a.2 King is on 3rd and intermediate (lets assume 0.5) level. Elevated King can move 4 steps in total when helped. Otherwise without help, can move 1 step only. However, King can also jump like horse because it has intermediate Rank.</p>
<p>King is the most powerful of all pieces, but in modern chess King moves 1 step only.</p>
<p>** Impersonators or Spies can move like any piece**</p>
<p>4.a Default moves of all Spies is 1. When they get elevated or helped, they can move like any piece on board. They can even jump over any piece, like horse. When helped or elevated, they can move secretly, even without breaking borders.</p>
<p>Sources: Agasthya smriti (obsolete) and samhita, Kautilya Arthshastra</p>
 17823: <ul>
<li>The <strong>king</strong> shouldn't rush into battles, but instead, he should go very slowly to beat his enemies.</li>
<li>The <strong>queen</strong> (<em>fers</em>) should guard the king and stay in his side. <sup>[1]</sup></li>
<li>The <strong>bishop</strong> (<em>fils</em>) are the elephants the king used to bring. They were moved diagonally to wound the ranks of their enemies. Because no one dared to face them, the fils could leap over intermediate pieces. <sup>[2]</sup></li>
<li>Good captains lead the ranks by turning <strong>horses</strong> to the right and left to guard their men and conquer the enemies.</li>
<li>The <strong>rooks</strong> (the ranks of the soldiers) go in whichever direction they like and as far as they think is best to conquer their enemies.</li>
<li>The <strong>pawns</strong> (the army soldiers) can't move too far because they carry their weapons. Some, however, can until they capture because afterward, they cannot do it. And this is like when ordinary people steal some things, that they carry them on their backs.<br />
The soldiers cannot wound an enemy in front of them, so instead, they wound (<em>capture</em>) the ones located diagonally that least expect it.</li>
</ul>
<p><sup><sup>[1]</sup> See <a href="https://en.wikipedia.org/wiki/Queen_(chess)" rel="nofollow noreferrer">Wikipedia</a> on the original movement of the queen.</sup><br />
<sup><sup>[2]</sup> See <a href="https://en.wikipedia.org/wiki/Alfil" rel="nofollow noreferrer">Wikipedia</a> on the original movement of the bishop.</sup></p>
<p>Source: <a href="http://jnsilva.ludicum.org/HJT2012/BookofGames.pdf" rel="nofollow noreferrer">this translated version</a>  of <a href="https://en.wikipedia.org/wiki/Libro_de_los_Juegos" rel="nofollow noreferrer"><em>Libro de los Juegos</em></a> (&quot;Book of Games&quot;), pages 8-9.</p>
