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For the last few version I’ve been implementing the ability to share game modes. Actually triggering a share was made user facing in 0.20 but the game could load them (with varying degrees of success) before then.

It was a multiple step process because it more-or-less requires a website to exist. For example if you visit this page it includes a link to “try opening in the app”. If you click the link on desktop it will take you back to the same place since that is the fallback page for the sharing link.

An additional feature I developed at the same time as sharing is the ability to embed little game mode widgets in the site.

Another thing I’ve been doing that uses the sharing link is creating YouTube videos of the interesting game modes feature the AI.

Sunday, May 3, 2020 Sun, May 3, 2020 03 May '20
Sharing settings in 0.21
  • Added new options to modify game to allow a variable number of human players.
  • Prevent AI from playing when popups displaying.
  • Fixed games not showing results with no humans.
  • Fixed AI not understanding misère.
  • Updated UI icons.
  • Added settings sharing.
  • Changing to a non-bounded topology now automatically enables “allow cell reuse”.
  • Added some network information to local network screen.
Friday, April 17, 2020 Fri, Apr 17, 2020 17 Apr '20
Release notes
App size over time

I have tried to be aggressive about keeping the size of the app down as it has grown. I made a specific decision early on to avoid image assets and I went through quite some hassle to enable build features to keep the code small.

A while ago Google introduced a new way to package and distribute Android apps called Android App Bundle.

Previously when distributing an Android app, the developer would produce an Android Application Package (often called an APK, based on its standard file extension) that included everything needed to run on a variety of Android devices. This could include things like assets at different resolutions and code for different device architectures that were not all needed on any single device.

It was possible to produce different APKs that were more specialized but it was quite a bit more effort to setup a build pipeline to produce them and distribute them. With App Bundles, Google Play does this for you. An App Bundle contains the same wide array of content for different devices, but Google Play generates a device specific APK for each device that downloads it.

The result is quite staggering - much more than I expected. The graph here shows the size of the app in MB over time, with the conspicuous drop at the end when I switched to using App Bundles. (One interesting thing to note is that the line splits into two at the end. The size is now slightly variable based on device and the split represents the smallest and largest APKs possible).

Saturday, April 11, 2020 Sat, Apr 11, 2020 11 Apr '20

The Android version is now distributed using an App Bundle on Google Play.

Saturday, April 11, 2020 Sat, Apr 11, 2020 11 Apr '20
Release notes

0.20.1 includes updated logic for “fairness calculations”. This has already been pushed for the server so this is in fact available in all versions when running with cloud simulation enabled.

This came about mainly because of my efforts to try and generate interesting game settings. My idea was to sort all the setting combinations by fairness, generate new ones based on them (via some minimal genetic algorithm), and then repeat until some good results fall out.

Early attempts

My first attempts did not work well. The game simulation works by playing a few turns using the normal AI, and then seeing what it thinks its chances of winning from the current position are. I defined “fairness” as: take the chance of winning of the best player and the chance of winning of the worst player, and then calculate the ratio of the two. Here are some of the types of games it generated at first:

  • Games with lots of players. Since nobody can win, it is perfectly fair.
  • Games with a win line that is too big to reach.
  • Games with a target score that is too big to reach.

Early fixes

I fixed some of it by doing some basic processing on settings before simulating. If the winline won’t fit, or there aren’t enough unique winlines to achieve the target score, I just reject it. Also, for now, I limited it to just two players.

The results were better, but basically just a more complex version of the above: games in which the AI did not manage to actually achieve a win in its simulations.

Refining the AI

One possible problem I identified was that the “chances of winning” calculation isn’t really about winning. It’s actually a kind of fuzzy number combining winning, and tying for first. In this case, tying for first is something I want to avoid. To fix this I parameterized the core AI engine, so the way it assigns a score to outcomes could be varied. There were initially two options:

  • Original AI: Winning scores 1, tying for first scores 0.5, everything else scores 0
  • “Win only” AI”: Winning scores 1, everything else scores 0

This means I can now look for games that have a high fairness, and a reasonably high chance of actually winning a game.

First derived game mode

Final updated AI

Separate to my goals of generating interesting game modes, I also took this opportunity to actually improve the AI. For games with more than two players, the (normal) AI now takes into account relative positions. So, for example with three players the following outcomes all have unique scores:

  • Finishing first, with no ties.
  • Tying for first.
  • Finishing second, with no ties.
  • Tying for second.
  • Finishing third.

This hopefully stops the situation in which multiplayer games ends up with several of the AIs “giving up” since they’ve determined they can’t possibly finish first.

Saturday, April 4, 2020 Sat, Apr 4, 2020 04 Apr '20
Improved popup in 0.20.1
  • Added new board size/topology selection popup.
  • Fix saving game copies.
  • Updated AI to take in account relative scores.
  • Changed fairness calculation.
  • Improved popup rendering.
Saturday, April 4, 2020 Sat, Apr 4, 2020 04 Apr '20
Release notes

It’s become a running gag that many commercial apps include release notes that just something like “Bug fixes and improvements”. Often it will be because there are lots of minor fixes that are too small and numerous to list. But just as often, there will be lots of technical changes that while important for various reasons, have no user facing effect. This post will attempt to explain some of the changes.

Xamarin Forms

Tic-tac-toe Collection depends greatly on a library called Xamarin Forms. This version updates it from version 3.4 to 4.4. There aren’t any major features in use yet, but there are a bunch of performance and stability improvements nonetheless.

Xamarin Essentials

This is a new dependency, and is partly the reason for the new Android 5 requirement. The key feature this brings is detection of light/dark mode, but it is also now used for launching external sites (for example: rating an app on iOS < 10.3 or accessing any web page on an Android device with Chrome custom tab support).


Android has long provided Android Support Library as a way of accessing new features on older versions of Android. AndroidX is conceptually just the next version of this. In practice, the implementation is very different and getting support for it in Xamarin has taken a while.


Several libraries have been removed.

Iconize by Jeremy Marcus is a library for using icon fonts in Xamarin Forms. I’ve used icon fonts since the very beginning and this library was a huge part of that. Enough of the functionality is now included directly in Xamarin Forms that the library is no longer needed.

Xam.Plugin.Connectivity and Xam.Plugin.Settings by James Montemagno superseded by Xamarin Essentials.

CarouselView.FormsPlugin by Alexander Reyes. For a long time, this was the best carousel view for Xamarin Forms, but it there is finally a version provided directly.

Acr.UserDialogs by Allan Ritchie provides system dialogs. After including Rg.Plugins.Popup for providing popup functionality, I switched to using that for simpler dialogs too for better style consistency.


There are handful of other libraries that have been updated just on the principle that staying up-to-date is better.

Wednesday, March 4, 2020 Wed, Mar 4, 2020 04 Mar '20
  • Added auto light/dark mode detection.
  • Made it so you can edit a player by tapping on the icon, not just the edit button.
  • Improved Gomoku and Drop Four rendering.
  • Reduce default zoom level for topology games.
  • Fixed the “rate app” link on iOS < 10.3.
  • Updated many libraries used by the app.

This version is not supported on Android 4.4 or earlier

Wednesday, March 4, 2020 Wed, Mar 4, 2020 04 Mar '20
Release notes

0.19.1 of Tic-tac-toe Collection drops support for landscape orientation on phones.

This has been difficult to support and made certain complicated screens (like the game setup screen) take much more effort for very little gain.

Tablets will still support landscape orientation, however there will no longer be a custom layout for landscape (on the few screens that did).

Tuesday, December 31, 2019 Tue, Dec 31, 2019 31 Dec '19
Black theme on iOS in 0.19.1
  • Added support for manually selectable light, dark and black themes. Automatically changing theme based on device setting will come later. The black theme uses true black for backgrounds, the dark theme uses a dark grey.
  • Cleaned up styling and color of the app throughout.
  • Removed support for landscape orientation on phones.

This will be the last version available on Android 4.4 (KitKat) or earlier. Future versions will require Android 5.0 (Lollipop) or later

Tuesday, December 31, 2019 Tue, Dec 31, 2019 31 Dec '19
Release notes