Principia 2026.09.19

Hello, Principia 2026.09.19 has been released. This is a minor update that brings a bunch of bugfixes, as well as introduces a couple of dialogs implemented using Imgui on Android.

As usual, you can find downloads on the Download page, and the full list of changes in the Changelog. F-Droid and various Linux distribution packages should receive the update within due time.

Imgui on Android

In the last release of Principia, the old GTK3-based dialogs used on desktop were entirely replaced with new ones implemented using Dear Imgui. This was a huge undertaking that had been in the works for years.

Now, the initial steps are being taken to replace the current dialogs used in the Android version with the same Imgui dialogs used on desktop, in order to fully unify the game's dialogs across platforms. A lot of the native Android dialogs have functionality missing compared to their Imgui counterparts and some aren't even implemented, so this will resolve many issues with parity in the Android version.

However, while Dear Imgui does support touch input, the general touch experience leaves a lot to be desired out of the box. I have brought over a patch from another fork of Dear Imgui which provides a smooth swipe-to-scroll like you would expect from a touch interface, and will likely end up doing other changes to ensure that the dialogs won't be a downgrade usability wise over the old native dialogs.

So the plan would be to gradually replace native Android dialogs with their Imgui counterpart once I have tested that they work well with touchscreen input, until the dialogs have all been fully unified.

For this update, the following dialogs use their Imgui implementation on Android now:

• Guard Point (previously unimplemented on Android!)
• Key Listener
• Animal
• Sandbox mode
• Event Listener
• New level

New Windows build pipeline

Now that we no longer depend on GTK3 on desktop, our dependency tree has been greatly reduced on Windows. This led to me completely redoing the way we make Windows builds, cross-compiling from Linux and building all our dependencies from source rather than using MSYS2 dependencies and compiling. This ends up being faster and gives us more control over the whole pipeline.

But what this really means is that now, the Windows build is even smaller (all libraries are linked together into a single executable now), and we also now have new 32-bit Windows builds.

32-bit Windows builds, in 2026? Well sure, now that we are in full control of our dependencies, we can confidently provide that now. While Windows 10 is still the minimum supported version, these new builds should also work as far back as on Windows 7 if you have all updates installed from Windows Update.

This is in line with previous efforts to get Principia onto new, old and niche platforms and devices now with the game's open source release.

If you are interested in porting Principia to some new, novel platform that we do not currently, see the Porting Principia page for a writeup about the dependencies for the Principia codebase. It's very portable, especially now with the Dear Imgui-based dialogs. Previously I have begun porting Principia to the Nintendo Switch which should hopefully be made available for download sometime in the future.

Bugfixes...

This update is mostly a bugfix update, and there are a lot of them. Here's a quick rundown for some of them:

The synthesizer's waveform generation has been fixed to not sound garbled on some platform such as Windows. Now you can safely listen to the various songs and renditions that the community has made using the synthesizer. There are an oddly high amount of Mega Man soundtrack renditions in the archive.

The Robot Manager's OUT0 and OUT1 sockets previously would report incorrect values for the adventure robot only when using touchscreen controls. This has now been fixed thanks to a contribution from chad64.

The Outdoor sky background now rotates along with the rest of the level when a Cam Rotator is active, thanks to a contribution from The4spaceconstants. The void colour in the Outdoor background has also been gamma corrected now.

If you would like to run multiple instances of Principia on desktop platforms you can now do so by launching Principia with the --ignore-pipe argument. Keep in mind this will make playing levels in the community site not launch it in the already running instance, and there may be issues with multiple instances of Principia accessing and writing user data at the same time. Using a portable build with isolated user data would be recommended.

For Android, the game now verifies HTTPS certificates with a bundled CA store when communicating with the community site so you know nobody is listening in on anything.

For a full list of changes in this release see the Changelog.

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Cover image: "Mini Golf Madness" by chad64