If you can change a chess rule or create a chess rule, what would it be ?

That rule sounds interesting. It would make passed pawns even more valuable, although in a wide majority of cases it would probably be better for the player that can promote the pawn to remain on his own side.

If what you mean is for the chess application to have speech recognition and execute spoken moves (essentially the reverse of spoken announcement of moves made), this is definitely feasible, though it's just a technical matter and not really a rule. Still, bear in mind that speech recognition can still be quite fallible, and you wouldn't want to risk a blunder just because the application happened to "mishear" you.

Generally speaking, issuing voice commands to a computer system is plagued by ambiguity, and (contrarily to popular beliefs) it probably will never be employed as widely as precise, clearly defined input (key presses, character entry, touch, etc.). 

If the King makes it to the opponent's 1st rank, it can be promoted to "Infinite Sheldon" and can teleport to any unoccupied space on the board for the remainder of the game.

everytime you take a piece you dont just take it off the board you shoot it with a sniper rifle until it flys off the board. Next you use the butt of the gun to move you piece onto the square =)

Any piece can retroactively capture any other piece moving through its threat, sort of like en passent, but for any piece with respect to any other piece on any move.

Pawns can also move backwards and capture diagonally in all 4 directions, but only on the move following a piece capture (Q, R, B, or N).

I would like the queen to have have the same movement rules as the king.

That would be a regression, considering that the queen used to be a ferz in the "old game" (i.e. before ~1475), a piece even weaker than a king (moving only one square diagonally).

By the huge response & number of wonderful suggestions it is obvious that the original designers of the game of Chess got it seriously wrong. So what we need is a total re-examination of the game.

I always get confused by having 2 Bishops, 2 Knights & 2 Rooks. Its annoying & I can never decide which one to move. So I propose replacing the Queenside ones with 3 new pieces.

1/- The Queens Bishop becomes the Archbishop. As it travels a lot the moves remain the same. Also as befits its status it can never be captured. To prevent it from becoming too strong & ruling the board its effect on the game is reduced by the fact that it cannot capture, it can only block progress of other pieces.

2/- The Queens Rook becomes the Troll. It hides under the board & captures & eats any piece landing on its square.

3/- The Queens Knight becomes the Griffin. Its move combines the powers of a Knight & Bishop as it can both run & fly. As its feathers can restore or enhance eyesight. Any piece it flies over can see where the Trolls are hiding. (Unless they move, then they disappear again)

Ok, now we have that part solved what about all those pesky pawns?

8 Pawns, are you kidding that's totally confusing, what idiot thought of that? Many times playing as White I have spent 20 minutes or more on the first move trying to decide which one to move 1^st. So the Pawns all become different Smurfs & each one has a different move. 2 moves forward, 1 move forward, one move diagonal left, 1 move diagonal right, 1 move left, 1 move right, 1 move backwards (Perfect for defending against back rank Mates) & finally 1 that doesn't move at all! All Pawns capture by moving like the ones on the left hand adjacent file.

So there you have it, simple, elegant & no more confusion over which piece to move.

Until they made a variant with the "Crazy woman" (i.e. modern queen rules). And that caught on!

Maybe King promotion. Then your opponent would have 2 kings to checkmate!

This sounds cool :)

its is good as it is

Allow 3 lifelines; one for consult the Chess engine, another for a blunder check, and lastly a time extension of at least 3 minutes. Applicable in tournament play of course. If one player hasn't used one lifeline and his opponent used just even one then the game is drawn, however if the two players both used the lifelines then the outcome is final.

Ppl forget that chess rules have only been a static a comparatively short time.

In order of preference...

1 players could agree to any "wild card" provision for a game.

2 pawns, like Q, could move any direction (but still only capture forward diagonally)

3 no one's allowed to beat ghostmirror

You, sir, are onto something! 

Pawns should not go straight. The new rule:

1. Pawns can move to the right and left but never straight.

2. Pawns take another piece directly in front of it.

It is the reverse of the current rule. Should be fun.

The king can switch place with any other pieces on the board. It's like Star Trek where the king is beamed up.

Beam the king up. Welcome to Star Trek Chess.

More women.

Not sure how to make that work out... but you just asked for the rule, not how it works.