Check out Chess with Different Armies, our featured variant for July, 2024.

This page is written by the game's inventor, Mark Hedden.

Mark E Hedden wrote to us in December 1999 regarding a very large chess variant he and a friend designed:

Hello again! Microorganism chess is a variant which has grown over the space of several weeks. I really thank my good friend, Bryan Weaver, who assisted me in the designing of this chess variant.



Microorganism chess is a chess variant that started in my head when I came up with a single piece: the Virus. Soon, I started trying to think of other pieces of the same type, and I got my friend, Bryan, involved with it. Over the period of about a week and a half, we slowly designed all the pieces of this variant, and then started fleshing it out into a full fledged chess variant. It has many unique pieces, and also is a very slow game, no matter how much you try to play it otherwise. However, I believe that the uniqueness of its pieces allows it to be fun anyway. And if you DO like slow games, well then, it's even better.


w a b t r v t a n t v r t b a w   16
p p p p p p p p p p p p p p p p   15
. . . . . . . . . . . . . . . .   14
. . . . . . . . . . . . . . . .   13
. . . . . . . . . . . . . . . .   12
. . . . . . . . . . . . . . . .   11
. . . . . . . . . . . . . . . .   10
. . . . . . . . . . . . . . . .   9
. . . . . . . . . . . . . . . .   8
. . . . . . . . . . . . . . . .   7
. . . . . . . . . . . . . . . .   6
. . . . . . . . . . . . . . . .   5
. . . . . . . . . . . . . . . .   4
. . . . . . . . . . . . . . . .   3
p p p p p p p p p p p p p p p p   2
w a b t r v t r n t v r t b a w   1

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

White: White blood cells, a1, p1; Amoeba, b1, o1; Bacteria, c1, n1; Platelet, d1, g1, j1, m1; Prions, e1, L1; Viruses, f1, k1; Paramecium, h1; Neuron, i1

Black: White blood cells, a16, p16; Amoeba, b16, o16; Bacteria, c16, n16; Platelet, d16, g16, j16, m16; Prions, e16, L16; Viruses, f16, k16; Paramecium, h16; Neuron, i16


There are many new pieces in this game. In fact, the only piece that remains the same from F.I.D.E. chess is the king (neuron)!

Viruses: The virus is the piece that started me off with this idea. It is a very interesting piece, and is potentially very powerful. Why? I shall explain in a moment. First, however, its move. The virus moves as does a King, a slow one square in any direction. Why is it so powerful, then? Well, because of what happens when it captures. It captures by moving into another pieces square, however, then the weird stuff happens. For two turns, the virus is taken of the board, while the piece that it takes remains on the board. However, after those two turns are up, the captured piece is removed from the board, and the virus is put back, along with a SECOND virus that can be put into any of the squares that are one space away from the first virus. Now do you see why it is so powerful? When it captures an enemy piece, not only does the enemy lose a piece, but you gain one.

Bacterium: The bacterium was the second piece that I made up for this game. I wanted to make it evolving, just like real bacteria evolve very quickly. However, it was difficult to pin down exactly how it would evolve. At first, I wanted to allow it to evolve at will, but then the number of limitations necessary in order to stop it from quickly becoming an Uber-piece. Finally, Bryan and I decided that it would just absorb the move of whatever piece it takes. However, all bacteria originally start out with the ability to move as either a king or a knight. However, if it, say, captures a virus, it then gets the special capturing powers of a virus, as well as the continued option to just capture normally. Often times, a bacterium can grow to become extremely powerful, but in others it can remain rather weak.

White Blood Cell: Well, with these two dastardly germs floating around our CV, it was only natural to soon include a defense mechanism. Thus, soon the White Blood Cell was born. This is a very powerful piece, with the ability to move as a Queen in regular chess. It has only one limitation: It can not move beyond its side's starting half of the board. This forces this piece into the defensive role it was meant for. It slows the game down a large amount, because of the fact that this piece makes attacks much more difficult than in normal chess.

Prion: The prion was the next piece to be included into the game. If you don't know what a prion is, it is an extremely small organism that is related to viruses, but is even simpler. Also, it can only be transferred between organisms by direct tissue transfer. This is important for its role in this game. The prion moves like a king, but can ONLY move to a square with another piece in it. However, that piece can be of either side. Once it has been moved, it 'infects' that piece. What that means is that it moves with that piece, and on any given turn it has the option of either staying in that piece, or 'killing' that piece. When it 'kills' a piece, that piece is removed from the board, but the prion stays on the board, and is left on the square that the other piece was last on. Also, when a piece that a prion has 'infected' is captured, then the prion infects the capturing piece. When a prion is just sitting on a square, then it can just be taken regularly. Obviously, a prion standing alone in the middle of the board is not a happy one.

Platelet: The Platelet is another very defensive piece. In the human body, a Platelet is a cell that heals wounds by forming scabs. It moves like a king (and also like many other pieces in this game). It captures regularly, as well. However, it has one special feature. If a Platelet is next to another Platelet, then they can combine to form an immobile wall. Also, if a lone Platelet is next to a wall, it can join that wall. However, remember, these walls are IMMOBILE, but they are also INVINCIBLE. A wall can be broken by simply moving one of the Platelets that is part of it out of the wall. However, it can be jumped over by jumping pieces, like the bacterium, and so it is not wise to simply surrond your neuron(king) with these, for it can be easily checkmated.

Amoeba: Amoeba are among the most powerful piece on the board. Their move is simple: They move either as a bishop or jump 3 spaces like a rook. But, it has one unique characteristic. It can expand from being a piece that takes up 1 square to a piece that takes up two squares orthoganally next to eich other. However, both of these squares must be empty in order for it to be able to expand. Once expanded, it can take two pieces in the same turn, and generally be very dangerous. Also, it can, once expanded, contract back to its original size.

Paramecium: A paramecium is a single-celled organism that is closely related to the Amoeba, but also has some important differences. It is not so fluid, but it has flagella that allows it to scoot along at a (relatively) quick pace. This quick speed has been carried over into its chess variant equivalent. It moves as either a regular chess rook, a regular chess knight, or it jumps 3 spaces like a bishop. The paramecium is easily the most powerful piece on the board at the beginning of the game, but a bacterium can become more powerful if it captures enough pieces. The paramecium has, besides its maneuverability, no special capabilities.

Red Blood Cell: The red blood cell is the pawn of this game. It moves exactly as a regular chess pawn, but it can move 1, 2, 3, or 4 spaces forward on its first move.

Neuron: This is simply the king under a different name.


There is, simply, no castling in microorganism chess. En Passant is exactly as in regular chess, except it can be done to pawns moved 1, 2, 3, or 4 spaces forward. If a bacterium captures a piece, it absorbs not only its movement capabilities but its special powers as well. I apologize for the lawyer-like text in the earlier part of this document, but some of these pieces have INCREDIBLY complex moves, and I wanted there to be as little confusion as possible.


Well, this variant has not been playtested very much (I will openly admit that), so I can only speculate on this part, but here is what I think will happen. If prions are used correctly, they can be incredibly useful if used correctly, but mastery of them is probably fairly difficult. A good idea is to have a prion hitch a ride on one of your Amoeba, because they will be used extensively, and could used the extra guarding power of a prion. Also, in this game, the openings are like molasses. They are very open, and pieces flow around well, but they flow around slowly. In the middle game, as more pieces are developed, it becomes more of a closed position, but in the endgame, it starts to get wild, as bacteria start to become more powerful, and viruses start to proliferate more. Also, remember that if there is a large group of enemy pieces, it is probably wise to attack them with viruses, because you will gain quite a few nice, shiny new viruses that way=D


I hope you enjoy this variant as much as I have. I would appreciate feedback of any kind. My e-mail adress is (email removed contact us for address), and Bryan's is (email removed contact us for address) .com
Written by Mark E Hedden.
WWW page created: December 6, 1999.