C++ CLI Micro Chess (Huo Chess)

• Download Huo Chess 0.721 Micro edition executable - 14.79 KB
• Download Huo Chess 0.721 source - 37.69 KB
• Download Huo Chess Opening Book - 1.24 KB

Summary

Huo Chess is a chess program of just 56.5 KB in size. Its current version (Huo Chess v0.721) can think up to 8 moves depth (4 half-moves for white and 4 half-moves for black pieces) and has an opening book capability. Huo Chess plays decent chess and has managed to draw Microchess, the first microchess from the Commodore era (see the Huo Chess Games Archive below). Its algorithm can be used to study the underlying logic of a chess program or as a basis for your own chess program (the source code is heavily commented and easily customized). The source code is continually improving and is distributed under The Code Project Open License. In this article, I also analyze its programming logic, with emphasis on the general flow inside the computer’s "mind," from the initial scanning of the chessboard up to the final decision on which move to play. Any comments are welcome!

Versioning

Huo Chess is intelligently designed, but it also evolves. Currently, the program is at version 0.721. The timeline of versions and the respective changes conducted in the program's code are depicted below.

Version 0.721	More thinking depth analysis capability has been added to the program. Huo Chess uses the ComputerMove2, ComputerMove4, ComputerMove6 and ComputerMove8 functions to think at a depth of 8 moves (4 half-moves for the white and 4 half-moves for the black pieces). Size: 56.5 KB
Version 0.6 (Micro edition)	It was based on version 0.6. Reduced all string/text (i.e. "White Rook" => "WR"). Reduced the length of variable names (in every variable in the program, specific strings were replaced with smaller ones). Icon was replaced with smaller one. Removed all unnecessary files (resources, assembly.cpp, stdafx, etc.). Size: 47.5 KB
Version 0.6	Removed the empty try...catch statement in line 3959 at HumanMove, which caused the bug at ElegxosNomimotitas not to show. Optimized the CountScore function. Fixed the bug at ElegxosNomimotitas in the part that checks moves of Rook-Queen-Bishop at lines 3143-32173. Added penalty in case the computer moves its pieces next to an opponent’s pawn. Made the computer eat the opponent’s queen when there is a chance. Lowered the value of the opponent’s king, so as to avoid the computer continuously going after him and sacrifice pieces for that,. Optimized the CountScore_Human function. Size: 53.5 KB
Version 0.5	Fixed HumanMove function. Optimized CountScore and ComputerMove functions. Size: 51.5 KB
Version 0.4	Added random playing capability. Optimized CheckForWhiteCheck and CheckForBlackCheck functions. Size: 51.0 KB
Version 0.3	Stronger playing capabilities. Added opening book capability. Optimized ElegxosNomimotitas and ElegxosOrthotitas functions. Size: 91.5 KB
Version 0.2	Fixed some bugs due to which computer played illegal moves. Thanks to everyone who gave me feedback! Size: 99.5 KB
Version 0.1	Initial version. Known problems: the program plays some illegal moves sometimes. Not too strong at all. 49.0 KB

Introduction

What is most important when you program? Is it the program design? Yes? If "yes," then why is that every program today is bigger than 123876 GB and requires 120987 MB of RAM to run? Why is every new project and program — by default — larger in size and slower in speed than the previous version? The answer is simple: because of the increasing speed of computers, no one actually cares about optimizing the code structure and the software design, since the new processor will definitely make the program look fine for the end user. During the time of Commodore computers, memory was rather limited. That is why programmers tried to make the code small and efficient. This resulted in Microchess, which was a very efficient, small (as the name "micro," which means "small" in Greek, implies) chess program that was able to play chess in the few KB available in computers of that time.

What I Accomplished

Driven by the above, I started developing a program in CLI C++ v8.0 (with Visual Studio 2008 Express Edition) to play chess with the intention of making a small in size (Micro)chess, even smaller than the Commodore-era Microchess. I named it "Huo Chess" for personal reasons. The program plays decent chess, but unfortunately will probably lose if it plays with Garry Kasparov. Its size is currently 56.5 KB, while the respective emulation of Microchess in C is 56 KB. However, it must be noted that the original Microchess, written in pure Assembly, was about 1 KB…something that I believe no one will ever match! In matches against Microchess, version 0.4 has managed to draw Microchess (see below the section of Huo Chess Games Archive).

How to Customize - Optimize the Program

The program has an opening book capability, which means that anyone can optimize the program by adding his/her own opening moves data in the respective folder Huo Chess Opening Book (which should be in the same directory with the executable). You can also add more thinking depth capability, by adding new ComputerMove functions (like ComputerMove2, ComputerMove4 etc.), change the value of ThinkingDepth variable and make the necessary adjustments to the HumanMove function (add another if at the point where it calls the ComputerMove functions). Moreover, you can also optimize the way Huo Chess thinks by changing the CountScore function and the way the computer values the pieces or the chessboard position. For example, if you change the score of the Queen in the CountScore function from 9 to 12, then the HY will play aggressively to attack the opponent's queen and at the same time try harder to defend its own queen. You can also — for example — give a high scoring to the existence of an opening column with a rook controlling it, so as to make the computer play more with its rooks and try to take over columns with them. Any FEEDBACK is WELCOME with better configurations of the Opening Book or the CountScore function!

I. Chess Algorithm Analysis

The algorithm used in this program for the implementation of the computer thinking is the "Brute Force Algorithm." Huo Chess plays with the material in mind, while its code has some hints of positional strategic playing embedded. More analytically: When the program starts thinking, it scans the chessboard to find where its pieces are (see ComputerMove function) and then tries all possible moves it can make. It analyzes these moves up to the thinking depth I have defined (via the ComputerMove -> HumanMove -> ComputerMove2/ ComputerMove4/ ComputerMove6/ ComputerMove8 path), measures the score (see CountScore function) of the final position reached from all possible move variants and – finally – chooses the move that leads to the most promising (from a score point of view) position (ComputerMove function).

More analytically, a high-level example of the progress of the main algorithm is as follows:

1. ComputerMove: scans the chessboard and makes all possible moves
2. CheckMove: checks the legality and correctness of these possible moves
3. (if thinking depth not reached) => call HumanMove
4. HumanMove: checks and finds the best answer of the human opponent
5. ComputerMove2: scans the chessboard and makes all possible moves at the next thinking level
6. CheckMove: checks the legality and correctness of these possible moves
7. (if thinking depth not reached) => call HumanMove
8. HumanMove: checks and finds the best answer of the human opponent
9. ComputerMove4 /ComputerMove6 / ComputerMove8: scans the chessboard and makes all possible moves at the next thinking level
10. CheckMove: checks the legality and correctness of these possible moves
11. (if thinking depth reached) => record the score of the final position
12. (if score of position the best so far) => record the move as best move
13. The algorithm continues until all possible moves are scanned

You can SET huo_debug to TRUE to see live the progress of the computer thought while the computer thinks. Just press a key to move step-by-step into the Huo Chess inner mechanism… You can also uncomment the code lines that record the time the program requires to think its move, so as to have an idea of the time required by the processor to complete the thinking process.

II. Huo Chess Thought Flow

Below, I analyze the thought flow of the chess program. I will describe only the main steps and code segments, so as to show the way the computer scans the chessboard, conducts all possible moves and finally finds the better one. The function names appear in bold, i.e. ComputerMove - Start indicates the beginning of the ComputerMove() function. Be aware that some code segments may be slightly different from the code in the distributed ZIP file since I continuously change the program. As it appears, the "constant beta" state is the trend nowadays.

ComputerMove - Start

1. If the first time called -> store initial position.

   if( Move_Analyzed >Thinking_Depth)
       Stop_Analyzing = true;
   
   if( Stop_Analyzing = false)
   {

2. Scan the chessboard.

   for iii, jjj

3. If a piece of the colour of HY is found, call CheckMove to measure how good it is.

Call: CheckMove

CheckMove

4. Number of moves analyzed ++.
5. Check correctness and legality of move.
6. Check if possible mate exists.
7. If move is legal and correct, then do it.
8. Check if a pawn must be promoted.
9. Store move to ***_HY variables, because after many calls of ComputerMove and CheckMove functions, the initial values of the move analyzed will be lost.

10. HY_Kobei_Kommati = false;
11.
12. if((ProsorinoKommati->CompareTo("White Bishop") == 0) ||
13. (ProsorinoKommati->CompareTo("Black Bishop") == 0))
14. {
15. HY_Kobei_Kommati = true;
16. Kopsimo_Kommati_Human_value = 3;
17. }
18. elseif((ProsorinoKommati->CompareTo("White Knight") == 0) ||
19. (ProsorinoKommati->CompareTo("Black
20. Knight") == 0))
21. {
[...]

22. If this is the first move analyzed, then record it as the correct "best" move, no matter how bad it is.

23. if((ProsorinoKommati->CompareTo("White Queen") == 0) || (
24. ProsorinoKommati->CompareTo("Black Queen") == 0))
25. this->eat_queen = true;
26. else this->eat_queen = false;
27. if(Move_Analyzed = Thinking_Depth)
28. {
29. // Measure the score of the move and record it as best move, if
30.
31. // it is larger than the score of the so-far best move score.
32.
33. }
34. if(Move_Analyzed <Thinking_Depth)
35. {
36. Human_is_in_check = false;
37.
38. WhiteKingCheck = CheckForWhiteCheck(CMSkakiera);
39. if( (this->m_PlayerColor->CompareTo("White") == 0) && (
40. WhiteKingCheck == true) )
41. Human_is_in_check = true;
42.
43. BlackKingCheck = CheckForBlackCheck(CMSkakiera);
44.
45. if( (this->m_PlayerColor->CompareTo("Black") == 0) && (
46. BlackKingCheck == true) )
47. Human_is_in_check = true;
48.
49. Move_Analyzed = Move_Analyzed + 1;
50.
51. Who_Is_Analyzed = "HY";
52.
53. for(i = 0; i <= 7; i++)
54. {
55. for(j = 0; j <= 7; j++)
56. {
57. Skakiera_Move_After[(i),(j)] = CMSkakiera[(i),(j)];
58. }
59. }
60. // Call HumanMove to find the best possible answer of
61.
62. // human opponent to the move currently analyzed
63.
64. // by the computer thought process
65.
66.
67. this->HumanMove(Skakiera_Move_After);

HumanMove

• Scan the chessboard -> find any possible move.
• Call CheckHumanMove.

CheckHumanMove - Start

voidCheckHumanMove(array<String^, 2>^ CMSkakiera_Human_Thinking)

Measure move score (if it is legal and correct) -> record the move as "best" move if its score is larger than the so-far best possible human move.

Human_Kobei_Kommati = false;
if((m_FinishingColumnNumber == this->m_FinishingColumnNumber_HY) && (
m_FinishingRank == this->m_FinishingRank_HY))
{
if((ProsorinoKommati->CompareTo("White Bishop") == 0) || (
ProsorinoKommati->CompareTo("Black Bishop") == 0))
{
Human_Kobei_Kommati = true;
[...]

Possible_mate = false;
if( Human_is_in_check == true)
{
WhiteKingCheck = CheckForWhiteCheck(CMSkakiera_Human_Thinking);
if( (this->m_PlayerColor->CompareTo("White") == 0) && (
WhiteKingCheck == true) )
Possible_mate = true;
BlackKingCheck = CheckForBlackCheck(CMSkakiera_Human_Thinking);
if( (this->m_PlayerColor->CompareTo("Black") == 0) && (
BlackKingCheck == true) )
Possible_mate = true;
}

CheckHumanMove - End

Conduct the best human move found.

Move_Analyzed = Move_Analyzed + 1;
Who_Is_Analyzed = "HY";

for(i = 0; i <= 7;i++)
{
for(j =0; j <= 7; j++)
{
Skakiera_Move_After[(i),(j)]=Skakiera_Human_Thinking[(i),(j)];
}
}

if(Move_Analyzed == 2)
this->ComputerMove2(Skakiera_Move_After);
elseif(Move_Analyzed == 4)
this->ComputerMove4(Skakiera_Move_After);
elseif(Move_Analyzed == 6)
this->ComputerMove6(Skakiera_Move_After);
elseif(Move_Analyzed == 8)
this->ComputerMove8(Skakiera_Move_After);
// Call ComputerMove2 to find the best next move of the HY (deeper thinking

ComputerMove2 - Start

voidComputerMove2(array<String^, 2>^ Skakiera_Thinking_2)
{
// Same as…ComputerMove

if(Move_Analyzed == 0)
{
// Same as…ComputerMove
// If we haven't reached the desired level of analysis, then the
// HumanMove will be called again, then again the ComputerMove
// function etc.
}

else
{
// Return to the ComputerMove function of the 'previous' thinking
// level to continue the analysis
Move_Analyzed = Move_Analyzed - 2;
Who_Is_Analyzed = "HY";

for(i = 0; i <= 7; i++)
{
for(j = 0; j <= 7; j++)
{
Skakiera_Thinking[i,j] = Skakiera_Move_0[i,j];
}
}
}
}

ComputerMove2 - End

HumanMove - End

if( this->Move_Analyzed == 0)
{
Kommati_moved = MovingPiece_HY;
STHSIMO = false;
FirstCall_CheckStisimoMove = true;
FirstCll_CheckStisimoMove_2 = true;
eat_queen = false;
hy_eats_the_piece = false;
human_eats_the_piece = false;
Who_Is_Analyzed = "Human";
CheckStisimo(CMSkakiera);
}

CheckMove - End

// close for iii, jjj loops

// close if( Stop_Analyzing = false ) segment

13. If no legal move found, MATE!

14.ifMove_Analyzed = 0
{

15. Check if it is good to conduct castling.
16. "Redraw" the chessboard with the move found.
17. Move the rook next to the king, if castling occurred.
18. Check if a pawn is promoted.
19. Now it is the turn of the other player to play!

20.}
21.else
22.{
23.// Return to the ComputerMove function of the 'previous' thinking
24.
25.// level to continue the analysis
26.
27.Move_Analyzed = Move_Analyzed - 2;
28.
29.Who_Is_Analyzed = "HY";
30.
31.for(i = 0; i <= 7; i++)
32.{
33.for(j = 0; j <= 7; j++)
34.{
35.Skakiera_Thinking[i,j] = Skakiera_Move_0[i,j];
36.}
37.}
}

ComputerMove – End

III. Huo Chess Thought Flow Scenario

Below, I illustrate the step-by-step process of the computer's thought for a thinking depth of 2. Let's see the "step" boxes to understand the way the program is structured.

Scenario Details

• Computer Level: Maitre (Þ ThinkingDepth = 2)

ComputerMove - Start

Step 1

START

Move_Analyzed = 0

1. If the first time called -> store initial chessboard position.

2. if( Move_Analyzed >Thinking_Depth )
3. Stop_Analyzing = true;
4. if( Stop_Analyzing = false)

5. Scan chessboard.

for iii, jjj

6. Scan chessboard, find a piece of the HY , conduct move, check correctness and legality of move, and if all is OK, then call CheckMove to measure the score of the move.

Call: CheckMove

CheckMove - Start

4. Number of moves analyzed ++.
5. Check correctness and legality of move.
6. Check if there is a mate on the chessboard.
7. If the move is correct and legal, then do it.
8. Check if there is a pawn to be promoted.
9. Store move to ***_HY variables because, after many calls of ComputerMove and CheckMove functions, the initial values of the move analyzed will be lost.
10. If this is the first move analyzed, then record it as the correct "best" move, no matter how bad it is.

Step 2

IF result: FALSE

Move_Analyzed = 0

11. if(Move_Analyzed = Thinking_Depth)

12. Measure the score of the move and record it as "best" move if it is larger than the score of the so-far best move score.

Step 3

IF result: TRUE

Move_Analyzed = 1

13. if(Move_Analyzed <Thinking_Depth)
14. {
15. Move_Analyzed = Move_Analyzed + 1;
16.
17. Who_Is_Analyzed = "HY";
18.
19. for(i = 0; i <= 7; i++)
20. {
21. for(j = 0; j <= 7; j++)
22. {
23. Skakiera_Move_After[(i),(j)] = CMSkakiera[(i),(j)];
24. }
25. }
26. // Call HumanMove to find the best possible answer of human opponent to
27.
28. // the move currently analyzed by the computer thought process
29.
30.
31. this->HumanMove(Skakiera_Move_After);

HumanMove - Start

Step 4

Find the best answer of the Human.

Move_Analyzed = 1

• Scan the chessboard -> find any possible move.
• Call CheckHumanMove .

CheckHumanMove - Start

voidCheckHumanMove(array<String^, 2>^ CMSkakiera_Human_Thinking)

Count the score of the move and record it as "best" if its score is better than the so-far best move.

CheckHumanMove - End

Conduct the best move of the human.

Move_Analyzed = Move_Analyzed + 1;
Who_Is_Analyzed = "HY";

for(i = 0; i <= 7;i++)
{
for(j = 0; j <= 7; j++)
{
Skakiera_Move_After[(i),(j)]=Skakiera_Human_Thinking[(i),(j)];
}

Step 5

Move_Analyzed = 2

Step 6

CALL next ComputerMove function for next-level move analysis.

Move_Analyzed = 2

if(Move_Analyzed == 2)
this->ComputerMove2(Skakiera_Move_After);
elseif(Move_Analyzed == 4)
this->ComputerMove4(Skakiera_Move_After);
elseif(Move_Analyzed == 6)
this->ComputerMove6(Skakiera_Move_After);
elseif(Move_Analyzed == 8)
this->ComputerMove8(Skakiera_Move_After);

// Call ComputerMove2 to find the best next move of the HY (deeper thinking)

Step 7

Scan the chessboard and find the best move for the computer.

Move_Analyzed = 2

voidComputerMove2(array<String^, 2>^ Skakiera_Thinking_2)
{
// Same as…ComputerMove

if(Move_Analyzed == 0)
{
// Same as…ComputerMove
// If we haven't reached the desired level of analysis, then the HumanMove
// will be called again, then again the ComputerMove function etc.
}

Step 8

Return to a previous ComputerMove (i.e. ComputerMove4 calls ComputerMove2 ) function to continue the analysis.

Move_Analyzed = 2 (finally this variable will be equal to 0).

else
{
// Return to the ComputerMove function of the 'previous' thinking
// level to continue the analysis

Move_Analyzed = Move_Analyzed - 2;
Who_Is_Analyzed = "HY";

for(i = 0; i <= 7; i++)
{
for(j = 0; j <= 7; j++)
{
Skakiera_Thinking[i,j] = Skakiera_Move_0[i,j];
}
}
}

ComputerMove2 - End

HumanMove - End

CheckMove - End

// close for iii, jjj loop
// close if( Stop_Analyzing = false ) segment

14. If no legal move is found -> we have MATE!

Step 9

Play the move with the highest score. Now it is the Human's turn to play.

ifmove_analyzed=0

15. Check if it is good to conduct castling.
16. "Redraw" the chessboard with the move found.
17. Move the rook next to the king, if castling occurred.
18. Check if a pawn is promoted.
19. Now it is the turn of the other player to play!

20. else
21. {
22. Move_Analyzed = Move_Analyzed - 2;
23. Who_Is_Analyzed = "HY";
24.
25. for(i = 0; i <= 7; i++)
26. {
27. for(j = 0; j <= 7;j++)
28. {
29. Skakiera_Thinking[i,j] = Skakiera_Move_0[i,j];
30. }
31. }
}

ComputerMove – End

IV. Flowchart Summary

ComputerMove()
{

for
{
    // First level of thought
    CheckMove()
    {

    if (Move_Analyzed < Thinking_Depth)
    {
        Move_Analyzed++;
        // Find the best possible human move-answer and continue the thinking tree
        Find Best Human Move (HumanMove function);
        Move_Analyzed++;

            ComputerMove2()
            {
                for
                {
                    CheckMove();

                    // Think deeper if you haven't reached the thinking depth
                    if (Move_Analyzed < Thinking_Depth)
                        [Think deeper, if necessary!];

                    // Record move analyzed as Best Move, if it has the best score
                    if (Move_Analyzed = Thinking_Depth)
                        CountScore();
                        [Record if best move];
                }

            // Return to the initial level of thinking to start
            //analyzing a new thread
            if (Move_Analyzed = Thinking_Depth)
                Move_Analyzed = Move_Analyzed – 2;
    }
    }
}
}

V. Huo Chess Micro Edition

I attempted to create a "Micro edition" of Huo Chess by stripping the program off every unnecessary line of code or file. In particular, in order to reduce the size, I used Huo Chess version 0.6 and did the following:

1. Reduced all string/text in the program (i.e. "White Rook" => "WR")
2. Reduced the length of variable names (in every variable in the program, specific strings were replaced with smaller ones). I don't really know why, but this played a role! Try it your self to see...
3. Icon was replaced with smaller one
4. Removed all unnecessary files (resources, assembly.ccp, stdafx, etc)

With the above steps implemented, the size was reduced from 53.5 KB to 47.5 KB. However, the code of the program can't be read at all! There is a price for small code...

VI. Huo Chess Games Archive

That segment contains games played by Huo Chess versus other micro chess programs.

GAME 1

Date: 2007-11-11
Place: Athens, Greece
White: HuoChess v0.4 (with Opening Book) [as distributed by The Code Project]
Black: Microchess (as provided by BenLo Park)
Result: Draw by threefold repetition

1. d4 Nc6
2. d5 Nb4
3. Nc3 e5
4. Bg5 Qxg5
5. Nh3 Qg4
6. e4 Qh4
7. Be2 d6
8. Bb5+ Kd8
9. Nf4 Qxf4
10. h3 Nf6
11. f3 Qe3+
12. Be2 Bd7
13. f4 Qg3+
14. Kd2 Qxf4+
15. Ke1 Qg3+
16. Kd2 Qf4+
17. Ke1 Qg3+
18. Kd2 Qf4+
19. Ke1 Qg3+
20. Kd2 Qf4+
21. Ke1 [draw by threefold repetition]

GAME 2

Date: 2007-11-11
Place: Athens, Greece
White: Microchess (as provided by BenLo Park)
Black: HuoChess v0.4 (with Opening Book) [as distributed by The Code Project]
Result: Draw by threefold repetition

1. e4 e6
2. Qh5 d6
3. Bb5+ Ke7
4. Qg5+ f6
5. Qh5 h6
6. d4 g6
7. Qxg6 Nd7
8. Bf4 f5
9. exf5 Ndf6
10. fxe6 Bxe6
11. a4 Bg7
12. Qxg7+ Bf7
13. Qxh8 Bh5
14. Qg7+ Bf7
15. Nc3 h5
16. Nf3 Nh7
17. Nd5+ Ke6
18. c4 c6
19. Nc7+ Qxc7
20. d5+ cxd5
21. Nd4+ Ke7
22. Nf5+ Ke6
23. Nd4+ Ke7
24. Nf5+ Ke6
25. Nd4+ Ke7
26. Nf5+ Ke6
27. Nd4+ Ke7
28. Nf5+ [draw by threefold repetition]

GAME 3

Date: 2008-01-22
Place: Athens, Greece
White: Microchess (as provided by BenLo Park)
Black: HuoChess v0.5 (with Opening Book) [as distributed by The Code Project]
Result: Draw by threefold repetition

1. e2-e4 e7-e6
2. d1-h5 c7-c5
3. f1-b5 g8-f6
4. h5-e5 f6-g4
5. e5-f4 g4xf2
6. e1xf2 g7-g5
7. f4-e5 a7-a6
8. b5-c4 f7-f6
9. e5-g3 d7-d6
10. g1-h3 h7-h6
11. h1-e1 e8-e7
12. b1-a3 d8-b6
13. d2-d4 b6-a5
14. c1-d2 a5xd2+
15. e1-e2 d2xd4+
16. 16.f2-f3 d4xb2
17. a1-d1 b2xa3+
18. c2-c3 a3xc3+
19. c4-d3 a6-a5
20. f3-g4 e7-d7
21. d3-b5+ d7-e7
22. g3xc3 f8-g7
23. e2-f2 e7-f7
24. d1xd6 a8-a7
25. c3xc5 b8-c6
26. f2-f3 b7-b6
27. c5xb6 c8-d7
28. f3-c3 e6-e5+
29. d6xd7+ a7xd7
30. b5-c4+ f7-e7
31. b6-c5+ d7-d6
32. c3-d3 c6-d4
33. c5-c7+ d6-d7
34. c7-c5+ d7-d6
35. c5-c7+ d6-d7
36. c7-c5+ d7-d6 [draw by threefold repetition]

GAME 4

Date: 2008-02-22
Place: Athens, Greece
White: Microchess (as provided by BenLo Park)
Black: HuoChess v0.6 (without Opening Book) [as distributed by The Code Project]
Result: Draw by threefold repetition

1. Nf3 d5
2. Nc3 Qd6
3. Na4 Qf4
4. c3 Bd7
5. d4 Qe4
6. Ng5 Qg4
7. f3 Qh4+
8. g3 Qh5
9. Nc5 Bb5
10. b3 f6
11. Nge6 b6
12. e3 Bc6
13. Nd3 Bd7
14. Nxf8 Kxf8
15. Nf4 Qg5
16. Ne2 Nc6
17. f4 Qg4
18. h3 Qf3
19. Rh2 Nh6
20. Kd2 Nf5
21. Kc2 Qe4+
22. Kb2 Qf3
23. Kc2 Qe4+
24. Kb2 Qf3
25. Kc2 Qe4+

Huo Chess (even without Opening Book) managed to play a very good game, during which it played well-structured chess. It didn't conduct any wrong moves, didn't give up any pieces and had a better position than Microchess at the end of the game (when the threefold repetition resulted in a draw).

History

• 3 October, 2007 -- Original version posted
• 15 October, 2007 -- Version 0.2
• 22 October, 2007 -- Version 0.3
• 15 November, 2007 -- Version 0.4
• 25 January, 2008 -- Version 0.5
• 28 January, 2008 -- License info and download updated
• 28 February, 2008 -- Article content and downloads updated
• 3 July, 2008 -- Version 0.721 - Article content and downloads updated