Checkers Pro for Windows Phone 7

[bzamora]

Hi, if anyone is using Windows Phone, I wanted to let you all know that Checkers Pro is available (both in free and paid versions). It plays using English rules.

I think it is a a reasonable strong program -- the best that I could do with the limited resources on a phone. I manually tested it vs all iPhone checker apps, and all Windows Phone checker apps, and Checkers Pro won the majority of the games. It evaluates the equivalent of 700K boards/second, uses an opening book based on analyzing 22,000 master games, and has some cool graphics

It offers 8 difficulty levels and online play.

App link: http://www.windowsphone.com/en-US/apps/ ... 237de2db9e

Regards
The author,
Bernardo Zamora
http://berzamora.wordpress.com

[Ed Gilbert]

Hi Bernardo,

Which iphone app did you think played the strongest? I've been trying to find a decent checkers app for my iphone and most of them are very weak (because I can beat them and I'm not a strong player).

Is your app available for the iphone also?

-- Ed

[bzamora]

Unfortunately, my app is only available in Windows Phone.

I found no iPhone game with opening book, and even at the highest levels they were not too strong (I might be wrong, but did not find any).

The iPhone games that I thought were the best:

a) http://itunes.apple.com/app/checkers-pr ... 41947?mt=8 (nice UI, but AI has limits)

b) http://itunes.apple.com/us/app/fantasti ... 58410?mt=8 (awful UI, lots of bugs, but probably the strongest AI)

Regards

[Ed Gilbert]

I agree, Fantastic Checkers is stronger than most, and has a very frustrating UI to make moves with. I found an app that is stronger. The $0.99 version of Teeny Checkers is stronger than Fantastic Checkers. It searches between 1 and 4 seconds on its highest strength, and beats Fantastic Checkers in every game, although it got stuck in one winning ending moving a king back and forth and could not finish off the win.

I would like to find an app that has
- a display of search scores, so I can see what its evaluation is of the current position.
- an analysis mode, so that I can analyze a game
- a setup mode for analysis of arbitrary positions.

I could not an app with any of these features.

-- Ed

[bzamora]

Well, you piqued my curiosity, so I ran a (totally unscientific) test of 6 games with the two apps: Checkers Pro for Windows Phone in level 8, vs iPhone Teeny Checkers with the slider in highest difficulty, half where Checkers Pro started, half Teeny Checkers started.

The score?
Teeny Checkers won 3, 1 tie, and Checkers Pro won 2. This is a non statistically valid sample, but my gut feeling is that this is accurate. Teeny Checkers is very strong positionally, and even though Checkers Pro opening book gives it a slight advantage at the beginning, Teeny Checkers frequently can overcome it later in the game.

Other thoughts about Teeny Checkers:
- I had never tested Teeny Checkers as the name of the app 'hides' the strength of the AI engine, I would think that it needs a 'stronger' name to reflect the AI capabilities
- once during endgame, the app gave me two moves (it 'skipped' its move), so I had to play again and discard that game
- the app allows players to continue playing the king in the same move after it has become king (which I understand is not a valid move), so again I had to discard that game and play again
- I could not get the 'undo' button to work, not sure why. It never undid my moves.
- the UI/visuals are very hard on my eyes. After a handful of games I did not want to play it any more, and I even tried out the 5+ different graphic themes. Either the colors are too bright, or there is little difference in the tone of the pieces and the board and it is hard to see the pieces. Of course it all depends on personal preference.

One final thought about all the other features you'd like to see in a phone game. As a developer I have to balance the time spent on the UI vs time spent on the engine and in 'advanced' features, as most of the users are lower level. Only 0.9% of all the people that have played Checkers Pro have *ever* beaten at least once Level 8. I ran a quick query on the Checkers Pro high score database, and here is the rundown of the level/population:

1st column: Checkers Pro level (1=weakest, 8=very strong)
2nd column: # of players that have beaten at least once this level (so this means this is the 'maximum level they have ever achieved', even if it was only 1 game)

Lvl #plyrs % plyrs
POO* 6716 13.4%
1 23205 46.3%
2 7163 14.3%
3 5811 11.6%
4 1582 3.2%
5 1880 3.7%
6 438 0.9%
7 2895 5.8%
8 458 0.9%
Total 50148

*POO = played only once

Regards
Bernardo

[Ed Gilbert]

You're right about the teeny name. I only tried it because I was not having much luck with any other apps, and so installed almost every checkers app I could find. The free version of teeny has other problems. It is not strong at all, and it does not enforce the rule of forced jumps! There is no setting to enable/disable this, it just lets you make other moves when you should be forced to capture. The free version also hung up on me a few times causing me to have to kill it. So the $0.99 version is much better.

I also could not get the undo move command to work.

Interesting that you found it does not stop jumping when it crowns a king. I had not encountered that situation in a game so couldn't test it (and because no arbitrary position setups and no analysis mode). I found another app that had the same problem. I think it was Fantastic Checkers, but I don't have my notes here at the moment so I'm not positive about which one it was.

The board graphics did not bother me the way it bothered you, but I probably did not play as many games as you. Making moves with the UI was pretty good, better than most. I think the app that was the easiest to use for making moves was 3D checkers. As long as I was anywhere close to the checker I wanted to move it understood and did the right thing. Some of the other developers should study how that one works and improve their move entry code.

I understand about the market for a real analysis program being very small. For a smart phone it is probably a tiny percentage of users that will want these features.

You may have noticed in the description of teeny that its engine is based on Martin Fierz's simple checkers. You can get the full source code for simple checkers at Martin's web site. It is not a strong engine at all, compared to some of the strongest ones like kingsrow and cake. The eval function is quite simple, the search does not use a hashtable, and has no move ordering of any kind. It's also slow because it uses arrays for the board representation instead of bitboards. It is only meant to be a demonstration of how to write a checkers app that runs under CheckerBoard. I played a few games between teeny and kingsrow. In kingsrow I turned off the endgame databases and opening book, set the hashtable to its smallest size, and set the search time to "instant", which means it uses about 0.1 second per move, compared to the 1 to 4 seconds used by teeny. It easily won every game, and kingsrow was running on a 6-year old P4 that is slower than the processor in the iphone 4S. I thought about porting kingsrow to the iphone, but I'd have to buy a Mac and develop a UI using Objective-C, which I think would be a lot of work.

-- Ed

[bzamora]

Very interesting discussion Ed. I also tried the free version first of teeny checkers, but was too easy, with no options.

During all my previous app testing I found that ~80% of the phone apps don't implement correctly the rule to 'stop move when king becomes king and then can jump again'. Probably nobody complains about it to the developers . I did find that same issue also in Fantastic Checkers.

The first version of my program had the capability to set up your own board but I found out zero people used it (I had 8000 users at the time), and it took a lot of time to maintain, so I ended up removing the capability.

Porting to iOS is a lot of work, and a new app in an already crowded app store is probably not going to be make the app successful, so I've not thought about porting. I recall reading an article (maybe by Martin F?) about his port to Android, and he agreed that arriving late to the app market had made his checkers app not as successful as he expected, even though the engine was strong.

One advantage that Checkers Pro has is the online checkers gameplay. I get to play vs real players that are significantly higher level than myself, much stronger than any phone game. That is fun (though sometimes annoying as many of them quit when they see they are losing).

Regards
Bernardo
-B

[bzamora]

Well, you can also get Windows 8 (Win RT, also known as Windows Metro).

Checkers Pro is now also available on Windows 8.The game is a bit stronger on Windows due to more processing poder.



Bernardo

[Wishmaster]

Bernardo, are you looking into developing further towards international draughts, or do you intend to stay with the English rules?
I have an app for Windows phone for international draughts but when I'm sober I score 100% against it, and it would be nice to see some new apps for international draughts coming on the market

[bzamora]

Hi, I would love to, but unfortunately I am not planning on adding International Checkers support. The reason is that it would require a rewrite of pretty much all the game.

I coded the board in an 8x8 bitboard, and all the game is highly optimized for extremely high performance using this board representation. It took me months to perfect the algorithm. Changing to international checkers would mean redoing pretty much all the logic, all the way to how the game is stored (any game position can be stored in a few 64-bit variables - changing to international would require a different way of storing data).

-B

[Maurits Meijer]

Bernardo, are you looking into developing further towards international draughts, or do you intend to stay with the English rules?
I have an app for Windows phone for international draughts but when I'm sober I score 100% against it, and it would be nice to see some new apps for international draughts coming on the market

Have you tried the playing on http://slagzet.com/play? It's just a website and is suppose to work on a windows phone too. I am curious to learn what you think of this program. I'd also like to know what how the performance of the move generator is on your device. Feel free to check the perft score out at http://slagzet.com/perft.

[bzamora]

I tried the slagzet web page a few minutes ago on my (yellow) HTC 8X windows phone (I love the phone, by the way).

The game runs ok in the phone, you can touch the piece positions and they move. Due to being a web page, the graphics are not too nice, and the interface is very basic.

Below is the performance of the game. How does it compare to other phones or to a PC?
START POSITIONS:
1- 9 kN/s
2 - 40.5 kN/s
3-219 kN/s
4-152 kN/s
5- 218 kN/s
6-249 kN/s

TEST POSITION WITH 530 REDUNDANT MOVES
1. 0.25 kN/s
2. 5 kN/s
3. 90 kN/s
4. 104 kN/s
5. 269 kN/s
6. 237 kN/s

WOLDOUBY
1. 6 kN/s
2. 6 kN/s
3. 30 kN/s
4. 73 kN/s
5. 72 kN/s
6. 74 kN/s
7. 81 kN/s
8. 108 kN/s
9. 112 kN/s
10. 134 kN/s

Bernardo

[Wishmaster]

Bernardo, are you looking into developing further towards international draughts, or do you intend to stay with the English rules?
I have an app for Windows phone for international draughts but when I'm sober I score 100% against it, and it would be nice to see some new apps for international draughts coming on the market

Have you tried the playing on http://slagzet.com/play? It's just a website and is suppose to work on a windows phone too. I am curious to learn what you think of this program. I'd also like to know what how the performance of the move generator is on your device. Feel free to check the perft score out at http://slagzet.com/perft.

Better than the app I have but on level "Extra moeilijk" it still isn't really strong.

1.32-28 19-23 2.28x19 13x24 3.31-27 9-13 4.36-31 4-9 5.37-32 17-21 6.33-28 14-19 7.31-26 18-23 8.26x17 11x33 9.38x18 13x31 10.41-36 9-14 11.36x27 24-29 12.34x23 19x37 13.42x31 12-17 14.39-33 17-21 15.47-42 21x32 16.42-38 20-24 17.38x27 14-19 18.40-34 15-20 19.34-30 8-12 20.43-38 7-11 21.46-41 2-8 22.38-32 10-14 23.30-25 5-10 24.41-36 10-15 25.45-40 19-23 26.33-28 23-29 27.44-39 8-13 28.39-34 13-18 29.34x23 18x29 30.40-34 29x40 31.35x44 1-7 32.44-39 24-29 33.50-45 20-24 34.49-44 11-17 35.27-22 17-21 36.22-18 12x23 37.28x30 29-34 38.48-43 21-26 39.31-27 14-20 40.25x14 34x25 41.39-33 6-11 42. 43-38 25-30

Didn't think it was necessary to play further here.

[Maurits Meijer]

Thank you for posting those stats.
Surprisingly your phone is generating moves at twice the speed of a black ipad3.(I blame safari for this)

My pc is about ten times faster then your phone. But I have seen other pcs getting up to about 5,000 kN/s.
Some other stats are posted in viewtopic.php?f=53&t=2308&start=135

I think this move generator is pretty fast. The search and evaluation leave quite a bit to be desired.