Checkers Tutor 1.04, 1.05 etc.

The Android market has a developer console which tells developers how often their application has been downloaded, how many active installations of it there are, and how the application is rated by the users. These stats are interesting, but not really up to Google standards - for example, you have no clue about how your downloads are distributed over time, and I have been logging in to my dev console every night to see how my Checkers Tutor is doing (it would be so much nicer if daily/weekly/monthly stats were available...). I have noticed that whenever I publish an update of Checkers Tutor, the number of downloads increases massively. I can also see that the number of active installs increases too, so I guess that my app is more visible on the Android market for perhaps a day after an update (but this is pure speculation). Anyway, seeing that my download stats are disappointing, I will be making some incremental updates to Checkers Tutor in the hope of attracting more users (1.04 released, 1.05 going up tonight, and 1.06 already planned), and perhaps gaining visibility in the Android Market (which is probably a combination of downloads and rating, but again this is guesswork). One problem which all checkers apps seem to have in common is that many people don't know that you must capture if you can in checkers. Aart Bik's Checkers for Android is by far the most downloaded checkers app, and it seems that about half of it's comments are "stupid - computer cheats" or "don't install - can't make moves I want to". And the ratings are correspondingly low. Unfortunately, Aart put in an option to make captures optional in his program, which is a bit of a shame because these people should learn how to play checkers for real...

Checkers Tutor 1.03

I just published version 1.03 of Checkers Tutor on the Android Market. It has improved move input, displays the current level in the title bar, displays the last move with a blue arrow instead of not-so-nice highlighted squares, and fixes a bug in the arrow rendering for capture moves when the board is flipped. Behind the scenes, I cleaned up a bit again, but my board class is still a God Object which isn't nice. The screenshot below shows how it looks (still quite similar to version 1.0!).


Checkers Tutor has some features that are better than what I have in CheckerBoard

• The move input is smarter: clicking on a piece that only has one legal move immediately executes that move (like in CheckerBoard), but also clicking on a square that can only be reached by one piece executes that move (unlike in CheckerBoard). This is nice because on those tiny mobile phone screens it's probably not easy to input moves, and every click you can save helps.
  
• All legal moves can be displayed with yellow arrows to teach the rules.
  
• The last move played can be shown with a blue arrow.
  
• The beginner level attempts to reach a bad (but not immediately losing) position at all times. This should avoid frustration for beginners, who are usually not happy with my PC programs because they lose too often.
  

Some other things are not so nice yet:

• The checkers engine is not as strong as I would like it to be. A large part of this is the low speed of the hardware, but I must admit that I haven't worked too hard on improving my Java checkers engine. It will most probably be more than good enough for 99% of the users. Nevertheless, a small opening book and perhaps endgame databases up to 4 pieces would greatly enhance its play, as would some more work on the evaluation function.
  
• The game is not saved when you quit and return (or when you switch the display from portrait to landscape mode or vice versa), only the current position. You cannot undo any moves made in the last session.
  
• There is not much advice to help a novice what to do with the game after installation. I would like to add something like Tips on Startup to improve this.
  
• Move input is limited to touch, but perhaps on phones with small screens this is not practical, and adding keyboard support would be nice.
  
• And probably many other things that I forget...
  

However, my christmas holidays are coming to an end, so the next update will have to wait a bit.

Checkers Tutor 1.02

In the 5 days since the publication of Checkers Tutor for Android, I fiddled around with it a bit. I added a feature to display all legal moves in the current position (it claims to be a tutor after all...), and I fixed some minor bugs: v1.02 now also displays properly in the landscape mode and the board numbers scale better (also on hi-res devices). Behind the scenes, I cleaned up the user interface code a bit to make it more readable, maintainable and less bug-prone. As usual with this cleaning business, it never actually ends. My board class has more than 700 lines of code, and after reading Robert C. Martin's nice book titled Clean Code, I must assume that that is too much, and besides I find a couple of the code smells he lists in my code...
These things aside, I'm afraid that my Checkers Tutor has missed the boat anyway - it got 228 downloads in its first 5 days, which means nearly none compared to Aart Bik's Checkers for Android, which apparently got over 250'000 downloads in one year (see Aart's blog for more information). This is the usual punishment for coming late to the party - I could have published Checkers Tutor in August, but somehow felt I should still add zillions of features to make it better than Aart's app - in the end I never added these features, and the early bird has caught the worm - the attention of the Android Market, where often-downloaded programs are more visible, and thus go in a positive feedback loop.

Blog labels

I added labels to nearly all posts on this blog, so that it is now much easier to find specific information. I have no idea whether anyone might be looking for anything here, but if so, it will be much easier to find things now! I am a bit surprised that suicide checkers takes the top spot in the labels list to the right...

Checkers Tutor for Android published!

I finally got round to publishing my Android checkers program - it *should* be available on the Android market under the name "Checkers Tutor" - but since I don't have an Android phone I have no way of knowing whether it really is there!

CheckerBoard 1.7 & co.

I just published a new version of CheckerBoard on my website. CB 1.7 has some minor bugs fixed, and doesn't write to the program files - CheckerBoard directory any more, which was a problem with the UAC (user account control) of Windows Vista and Windows Seven. Most of the changes in CB 1.7 were contributed by Ed Gilbert; thanks a lot Ed!
The CB source code is also available, but still rather difficult to comprehend.

I also updated the engines to comply with Vista/Win7, Cake and the Kingscourt engine didn't work with the new OS versions unless run with administrator rights. The CB install package now also includes Suicidal Cake with a 4-piece endgame database for suicide checkers and an opening book. I worked on suicide checkers about 3 years ago, and thought it would be a shame to leave what might be the world's best suicide checkers program rot on the shelf...

CB and Windows 7

I'm writing this post on my brand-new Windows 7. Unlike Vista to which I took an instant dislike, this product seems to be much more user-friendly (UAC...) and the harddisk isn't working for about an hour after startup. Of course, the very first thing I did with Win7 was to test whether CheckerBoard was working on it, and it is - however, it has to be run as Administrator, otherwise it crashes. I think it was the same with Windows Vista (but I can't remember), and I hope I will have some time during the christmas holidays to sort out these issues.

Checkers for Android Phones

It's been a while since I worked on my Java program. Actually, the underlying purpose of writing a Java checkers program was to (1) learn Java and (2) write a checkers program for the Android operating system running on the Google phones. There are two checkers programs for the iPhone based on my simple checkers engine, and since developing for the iPhone seems to be a PITA or at least some kind of licensing hell, I was never interested. The much more open philosophy of Android attracted me however, and my checkers program is already running on my emulator. It manages to search about 5000 positions per second, i.e. it's nearly 1000x slower than my corresponding PC program, and therefore also quite a bit weaker. But since it incorporates a lot of the stuff that I learned during the many years of programming Cake, it plays a decent game nevertheless. I worked hard on it during the last two weeks on my mountain holidays (whenever I wasn't climbing the mountains), and it's already a working program. However, I may have overdone things a bit trying to put a lot of features into the program, so it won't be ready today or tomorrow, but hopefully before the summer is out.

Multi-core KingsRow tested

I have been testing KingsRow 1.16d against Cake 1.8x12 on my quadcore machine. Here are some results of engine matches at 5 seconds per move:

Cake 1.8x12 - KingsRow 1.16d (1 core)  +19 -14 =255
Cake 1.8x12 - KingsRow 1.16d (2 cores) +19 -18 =251
Cake 1.8x12 - KingsRow 1.16d (4 cores) +18 -19 =251

I had been expecting Cake to be slaughtered by the multi-core version of KingsRow, but apparently it's not that bad. To check whether or not it might be a bug in the multithreaded search of KingsRow, I played a match with Cake and KingsRow running on 1 core, but KingsRow got 10 seconds per move - so essentially this should reproduce the second match above. I found

Cake 1.8x12 - KingsRow 1.16d (10s)  +17 -21 =250

There is always some variability in engine matches, otherwise one might conclude that the 2-core version of KingsRow was not performing as well as KingsRow with twice the search time. As it is, I don't quite know what to make of it.

KingsRow goes multicore!

The amazing Ed Gilbert has done it again: he rewrote his KingsRow engine so that it can use multiple CPUs. While he was at it, he also fixed a few bugs in CheckerBoard. You can download a new version of CheckerBoard, and the multi-CPU-KingsRow on Ed's webpage. Enjoy!