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In an email, December 1999, Mark Hedden sent an email to us, with the following text:

Well, here is yet another Chess game from the twisted mind of Me, Mark Hedden.

IO CHESS

Introduction

Well, after making Ganymede Chess and Europan Chess, I sat back and thought. After a lot of thinking I decided that it would be absolutely wonderful to create a series of games on increasingly large boards, all with the same types of pieces, and all named after some object in the outer regions of our solar system. So, Io chess came to be. It is a violent game, with constant upheavals and sudden changes in who has the advantage. Io is one of Jupiter's moons, and it also is very violent. It has constant volcanic eruptions, and the geography of the world changes every few days. Of course, one of the weird things about my names is that Ganymede is the largest moon in the solar system, but it is the smallest of my variants. Oh, well.

Setup


g r s c n u b q k b u n c s r g  16
www . . i . . . . . . i . . www  15
p p p p p p p p p p p p p p p p  14
. . . . . . . . . . . . . . . .  13
. . . . . . . . . . . . . . . .  12
. . . . . . . . . . . . . . . .  11
. . . . . . . . . . . . . . . .  10
. . . . . . . . . . . . . . . .  9
. . . . . . . . . . . . . . . .  8
. . . . . . . . . . . . . . . .  7
. . . . . . . . . . . . . . . .  6
. . . . . . . . . . . . . . . .  5
. . . . . . . . . . . . . . . .  4
P P P P P P P P P P P P P P P P  3
WWW . . I . . . . . . I . . WWW  2
G R S C N U B Q K B U N C S R G  1

a b c d e f g h i j k l m n o p

WHITE: Griffin, a1, p1; Rook, b1, o1; Spider, c1, n1; Crooked Knight, d1, m1; Knight, e1, L1; Supercomputer, f1, k1; Bishop; g1, j1; Queen, h1; King, i1; Wall, a2-b2, o2-p2; Nightrider e2, l2; Pawn, a3, b3, c3, d3, e3, f3, g3, h3, i3, j3, k3, l3, m3, n3, o3, p3, k3, L3, m3, n3, o3, p3

BLACK: Griffin, a16, p16; Rook, b16, o16; Spider, c16, n16; Crooked Knight, d16, m16; Knight, e16, L16; Supercomputer, f16, k16; Bishop; g16, j16; Queen, h16; King, i16; Wall, a15-b15, o15-p15; Nightrider e15, L15; Pawn, a14, b14, c14, d14, e14, f14, g14, h14, i14, j14, k14, l14, m14, n14, o14, p14, k14, L14, m14, n14, o14, p14

Pieces

The Rook, Knight, Bishop, King, and Queen all move the same as they do in regular chess, except that all of them except the King promote. In fact, all pieces except the King promote in this variant. But, some of them promote in different ways then others, so watch out.

Griffin: The griffin is one of my favorite pieces, and has been included in both Ganymede Chess and Europan chess, as well as in Io Chess. It moves by first moving one square diagonally, and then by moving like a rook, but only away from its starting square. Or, to put it visually, it moves like this:

. . . + . + . . .
. . . + . + . . .
. . . + . + . . .
+ + + + . + + + +
. . . . G . . . .
+ + + + . + + + +
. . . + . + . . .
. . . + . + . . .

It can continue moving in any of the eight directions pictured in the diagram. It is among my favorite pieces, for some unknown reason, and the larger the board, the more open the position, the better this piece works. It is a fairly powerful piece, being worth about 7 pawns. In this game, it promotes by reaching your side's last row.

Hippogriff: This is the promoted form of the griffin. The griffin can be promoted to a hippogriff by reaching your sides last row, that is the row that most of the enemy pieces start out on, which is quite a feat because of how blocked in the griffin is in the opening position. However, once a griffin is promoted, it becomes immensely powerful. The hippogriff moves either as a griffin or a rook. This makes it a very, very powerful piece, worth about 12 pawns. It has control of three whole columns and three whole rows. It is veeeery powerful, so watch out for a griffin promotion. It can very, very easily checkmate a lone king with no help from any other piece.

Castle: The castle is one of the two promoted forms of the rook. It moves either as a rook, or it jumps two or three spaces diagonally. A rook is promoted to a castle right after you castle with it(!) It isn't an incredible improvement over the rook, but it is still an improvement, especially considering the fact that it does have some forward forking power, something completely absent from the rook. This promotion makes castling even more desirable than it is in regular chess, and there is almost no reason not to castle as soon as possible. I would guesstimate that it is worth 6 or 7 pawns.

Fortress: The fortress is the second promoted form of the rook. It is reached when either a castle or a rook reaches your sides last row of the board (Row 16 for white, row 1 for black). This is so that the rook that doesn't get castled can still be promoted, and so that the castle can become something even more powerful. It moves either as a rook, a knight, or by jumping two spaces diagonally. It is a big improvement over both the castle and the rook, being worth about 9 pawns.

Spider: The spider is another of my favorite pieces. It is, simply, the diagonal equivalent of the griffin. It moves by first moving one space like a rook, then any number of spaces diagonally away from it. This is the first variant I have put it in, but I like it enough that I will probably include it in more variants. To put its move graphically, it moves like this:

. + . . . . . + .
+ . + . . . + . +
. + . + . + . + .
. . + . + . + . .
. . . + S + . . .
. . + . + . + . .
. + . + . + . + .
+ . + . . . + . +

It can continue moving in any of the eight directions in the diagram. It is a weird piece, I assure you, but it is also very powerful. It is slightly less powerful then a griffin, but the difference isn't that noticable, being about half of a pawn less, or maybe a full pawn at the very most. It's main problem is that it always has to switch colors after every move, and also that it is a bit more awkward than the griffin. However, it is still a very powerful and very useful piece. Another difference between it and the griffin is that the spider is much easier to develop then the griffin. A spider promotes to a tarantula upon reaching the last row of the board.

Tarantula: The tarantula is the promoted form of the spider. A spider is promoted to a tarantula upon reaching the last row of the board. Just as the hippogriff is a combination of a griffin and a rook, the tarantula is a combination of a spider and a bishop. It is a very powerful piece, worth about a pawn less then a hippogriff, or about 11 pawns. It can easily checkmate a lone king without help from even its own king, so a tarantula in the endgame is a very nasty piece which needs to be watched out for.

Crooked Knight: The crooked knight is an interesting piece. It starts out by making a knight move, but then it turns and makes another knight move away from itself. However, that's not a very good explanation for it, so just look at the diagram to figure it out.

. . . . . + . + . . . . .
. . . . . . . . . . . . .
. . . . . . + . . . . . .
. . . . . . . . . . . . .
. . . . . + . + . . . . .
+ . . . + . . . + . . . +
. . + . . . C . . . + . .
+ . . . + . . . + . . . +
. . . . . + . + . . . . .
. . . . . . . . . . . . .
. . . . . . + . . . . . .
. . . . . . . . . . . . .
. . . . . + . + . . . . .

It can keep on doing that until it reaches the end of the board. It is a very interesting piece, being sort of a rookish knightrider. The crooked knight is a very powerful forking piece, being able to fork multiple pieces far away from it. One of the problems with it is that we are not that used to a move like this, so it is easy to get surprised by them. However, if you do manage to remember them and use them well, they can be very dangerous. It promotes to a crooked paladin after it reaches the row where the enemy pawns start out. I'd say that it is worth about as much as a traditional knightrider, or about 6 pawns, maybe one more on this larger board.

Crooked Paladin: The crooked paladin is the promoted form of the crooked knight. It moves either as a crooked knight, or as a (3,1) jumper. A crooked knight is promoted to a paladin when it reaches the row where the enemy pawns start out at. It isn't a gigantic improvement over the crooked knight, but it is still an improvement. I'd have to say that it is worth 9 pawns, but in some situations it could be worth 10.

Gnu: The gnu is the promoted form of the knight. A knight is promoted to a gnu when it reaches either the 8th or 9th rows. I made it so easy to promote a knight because, well, it isn't. On this big board, it takes a knight quite a while to get this far, so I think that this is a reasonable place to promote them to a not-incredibly-powerful piece. The gnu is a combination of a knight and a (3,1) jumper. It is worth about 5 pawns, but in closed positions it can be worth much more. However, in this game, closed positions are not that common, so while the gnu is an improvement over the knight, not by a terribly gigantic amount. However, it is powerful enough that it would be OK to sacrifice several pawns in order to get a chance to promote this piece.

Supercomputer: The supercomputer is a piece that I included from Europan Chess, because I like it a lot. For the reason behind the name, please see the description in Europan Chess. It moves in one of three ways. It either jumps three spaces like a rook, two spaces like a bishop, or as a (3,1) jumper. It is worth about 4 pawns. It is an interesting piece, being one of the few pieces who has no truly close range moves, but also no truly long range moves, but is a mid-ranged piece. Because of this, it is a piece that is wonderful in the opening, and should be among the first pieces you develop.

Quantum computer: The quantum computer is the promoted form of the supercomputer. A supercomputer is promoted to a quantum computer when it reaches the row that the enemy pawns start out on. A quantum computer moves either as a supercomputer, a non-royal king, or a knight. As you can see, the quantum computer is a powerful medium and short ranged piece. It can dominate in closed positions, and even in open positions it can be useful. It is worth about 6 pawns, a whole pawn more than a rook, although in closed situations it is worth almost as much as a queen.

Archbishop: The archbishop is the promoted form of the bishop. It moves as either a bishop or a knight, and a bishop promotes to one when it reaches the row that the enemy pawns start out on. It is a rather powerful piece, being worth slightly more then a rook. It is extremely useful in any situations, and there are some situations where you could even perform a knight sacrifice to get one. In general, it is probably worth a bit more then a separate knight and bishop, so you could probably trade a knight to promote a bishop.

Empress: The empress is the promoted form of the queen. It moves as either a queen, a knight, or a (3,2) jumper, and it is reached when a queen moves to its sides final row. It is a very powerful piece, with incredibly gigantically large forking ability. If you can manage to promote a Queen to one of these you have secured a big advantage, equivalent to about 5 or 6 extra pawns. Over all it is worth about 14 pawns, an incredible piece.

Wall: The wall is a piece that from Ganymede Chess, and is among my favorite pieces. Its move is simply that of a rook, but it has one special property. You see, the wall takes up two squares. This makes it a wonderfully unusual piece. It starts out taking up two squares horizontally next to each other, but it can rotate to take up to squares vertically next to each other. But it can never take up two spaces diagonally. And, before you ask, yes it can take two pieces in the same turn. Remember, however, that it is easier to take than most other pieces, because it can be more easily threatened. However, after some practice, you should start to get used to it. It promotes to a fortress upon reaching the eighth or ninth rows. I made it promote so easily because it isn't really a good opening piece, so any attempt to promote it early will probably result in either its loss, loss of incredible amounts of time, or both.

Great Wall: The great wall is the promoted form of the wall. It is the same as the wall, except that it has the added power of being able to take up two squares diagonally adjacent to each other, and the ability to move one square diagonally. It is worth about 6 pawns.

Nightrider: The nightrider is a powerful piece that is used in many chess variants. It moves by first making a knight move and then making continual knight moves of the same type away from it. It must stop if it captures a piece. The nightrider is a fairly powerful piece, worth about a pawn more then a rook. It can be useful in almost any situation. In closed situation its jumping ability makes it useful, and in open situations its long range movement powers make it powerful. It promotes to a moonrider upon reaching the row where the enemy pawns start on.

Moonrider: The moonrider is the promoted form of the nightrider. It moves either as a nightrider or a (3,2) jumper. It is a powerful piece, worth about as much as a Queen. You really need to watch out for nightriders, cause in an open situation they can suddenly sneak up on you and capture one of your pawns, and then promote to a moonrider and get really powerful.

Pawns: Pawns move the same as do pawns in regular chess, except that they can move up to 5 squares forward on their first move. Also, after they have made the long trek to the opposite side of the board (16th row for white, 1st row for black), they can promote to any of the pieces that start on the board or their promoted forms, plus one new piece, the very powerful Octospider, which moves either as either a griffin or a spider. You will normally want to promote it to an Octospider, which is the strongest piece in the game.

Special moves

Castling occurs when there are no more pieces between the king and the rook. The king then moves to the square where the spider starts out at, and the rook moves one square beyond the King and then immediately promotes to a castle. Promotion occurs on the same turn as a piece fulfills the criteria required for its promotion.

Strategy

In Io Chess openings, development is key. With some powerful pieces floating around the board from move one, if you don't have enough pieces in good squares, you could get trampled flat. Of course, castling here is even better than in regular chess, because you automatically gain material whenever you castle, because of the rook promotion. You should view as risky, however, any opening whose purpose is simply to promote a knight to a gnu. Your time disadvantage will be tremendous, and will not be worth the material gain. However, once you are securely developed, go ahead and promote a knight! Also, those pieces that promote by reaching the enemie's pawn row can often be safely promoted in the middle game. Again, do so. It will get you a material advantage, the equivalent of taking several pawns, but often far more useful. Also, watch out for crooked knights and nightriders! These long-range pieces can sneek up on you all of the sudden, and they can make you suffer. Of course, they can also make your opponent suffer. Of course, if you are not very good at using them, trade them off for one of the opponents bishops or spiders early in the game. Bishops and spiders tend to develop early, which is good because they work well in the opening. Also, supercomputers are as easily developed as knights are in normal chess, which is also good, because they work well with pawns, and even better with far-advanced center pawns. Also, with all these pieces, pawn structure becomes less important then piece play, unless you are really trying very hard to slam the position closed.

Notation

Notation is same as in regular chess, except for the new pieces. The symbols for the new pieces are: C for castle, F for fortress, G for griffin, H for hippogriff, S for spider, T for tarantula, CN for crooked night, CP for crooked paladin, GN for gnu, SC for supercomputer, QC for quantum computer, A for archbishop, W for wall, GW for great wall, NN for nightrider, MN for moonrider, and O for Octospider. Pawns aren't normally symbolized by a letter, but if you want one, P works fine. For Wall rotating, write W, then the letters of the squares they used to take up, followed by a dash, and then those they now take up.

Sample game

I'm actually including a sample game. No assurance on quality here, just some basic ideas on how to play Io chess. The diagrams for the pieces will be weird, but try to follow along.
1. m6; SC-j13

g r s c n u b q k b . n c s r g  16
www . . i . . . . . . i . . www  15
p p p p p p p p p p p p p p p p  14
. . . . . . . . . u . . . . . .  13
. . . . . . . . . . . . . . . .  12
. . . . . . . . . . . . . . . .  11
. . . . . . . . . . . . . . . .  10
. . . . . . . . . . . . . . . .  9
. . . . . . . . . . . . . . . .  8
. . . . . . . . . . . . . . . .  7
. . . . . . . . . . . . P . . .  6
. . . . . . . . . . . . . . . .  5
. . . . . . . . . . . . . . . .  4
P P P P P P P P P P P P . P P P  3
WWW . . I . . . . . . I . . WWW  2
G R S C N U B Q K B U N C S R G  1

a b c d e f g h i j k l m n o p

White's first move opens up lines for his spider and a niche for his knight; black's develops a piece. If they ever write books on this (yeah, right), I hope 1. m6 is called the Hedden Opening.

2. S-j6; NN-i7
3. h6; NN-g11

g r s c n u b q k b . n c s r g  16
www . . . . . . . . . i . . www  15
p p p p p p p p p p p p p p p p  14
. . . . . . . . . u . . . . . .  13
. . . . . . . . . . . . . . . .  12
. . . . . . i . . . . . . . . .  11
. . . . . . . . . . . . . . . .  10
. . . . . . . . . . . . . . . .  9
. . . . . . . . . . . . . . . .  8
. . . . . . . . . . . . . . . .  7
. . . . . . . P . S . . P . . .  6
. . . . . . . . . . . . . . . .  5
. . . . . . . . . . . . . . . .  4
P P P P P P P . P P P P . P P P  3
WWW . . I . . . . . . I . . WWW  2
G R S C N U B Q K B U N C . R G  1

a b c d e f g h i j k l m n o p

4. B-c8; e10
5. N-m3; B-b11
6. d7;  h12
7. S-i8; B-d10
8. SC-f4; d11
9. CN-k2; S-f12

g r . c n u . q k b . n c s r g  16
www . . . . . . . . . i . . www  15
p p p . . p p . p p p p p p p p  14
. . . . . . . . . u . . . . . .  13
. . . . p s . p . . . . . . . .  12
. b . p . . i . . . . . . . . .  11
. . . b . . . . . . . . . . . .  10
. . . . . . . . . . . . . . . .  9
. . B . . . . . S . . . . . . .  8
. . . P . . . . . . . . . . . .  7
. . . . . . . P . S . . P . . .  6
. . . . . . . . . . . . . . . .  5
. . . . . U . . . . . . . . . .  4
P P P . P P P . P P P P N P P P  3
WWW . . I . . . . . C I . . WWW  2
G R . C N . B Q K . U . . . R G  1

a b c d e f g h i j k l m n o p

Both sides have so far developed peacefully; That is about to change.

10. Sxg11; hxg11
11. SC-j4; NN-i9
12. 0-0; CN-e10
13. Bxe10; dxe10

g r . . n u . q k . . n c s r g  16
www . . . . . . . . . . . . www  15
p p p . . p p . p p p p p p p p  14
. . . . . . . . . u . . . . . .  13
. . . . p s . . . . . . . . . .  12
. b . . . . p . . . . . . . . .  11
. . . b . . . . . . . . . . . .  10
. . . . . . . . i . . . . . . .  9
. . . . . . . . . . . . . . . .  8
. . . P . . . . . . . . . . . .  7
. . . . . . . P . S . . P . . .  6
. . . . . . . . . . . . . . . .  5
. . . . . U . . . U . . . . . .  4
P P P . P P P . P P P P N P P P  3
WWW . . I . . . . . C I . . WWW  2
G R . C N . B Q . . . . A K . G  1

a b c d e f g h i j k l m n o p

In this position, white probably has the advantage. His king is safely castled, giving him a castle that will become useful as soon as he move the knight in front of it. He is well developed, having many pieces out, and many more pieces back at home, but in good defensive squares. He has a very small material advantage. In fact, black's only real plus is the removal of white's active bishop, and a very tiny time advantage. All the real action is taking place on the queenside, and white is happy to leave it there, well away from his king. Black, however, needs to develop more, and castle quickly, because white can probably make some good attacks pretty soon. However, you may disagree with my assessment. If you do, please tell me.

Postscript

Thank you for reading my insane babbling, and (hopefully) being interested in it. I will appreciate any and all feedback that you have, please e-mail it to (email removed contact us for address) cago.avenew.com.
Written by Mark Hedden. Conversion to html by Hans Bodlaender.
WWW page created: January 6, 2000.