OpenSA2 0.1.0-alpha.3.1

OpenSA2 0.1.0-alpha.3.1 lets the renderer run on phones whose graphics driver offers only Vulkan 1.1, and fixes the white Chao in the Chao Garden.

You must supply your own unmodified PC game installation: the version Steam sells and installs today. These downloads include recompiled game logic and the port's runtime. They contain no original game executable or assets.

What's new

Vulkan 1.1 phones. Phones whose graphics driver offers only Vulkan 1.1 or 1.2, such as those with an Adreno 610 or 644, stopped before the first frame because the renderer asked for Vulkan 1.3. When no device takes the 1.3 request, the renderer now uses a reduced Vulkan 1.1 profile. Its shaders are rewritten for the older driver, and anything that can't be rewritten is refused by name instead of drawn wrong. Phones with Vulkan 1.3 draw exactly as before. The 1.1 profile is new and has not yet run on a real Vulkan 1.1 phone, so a crash report from one would help a lot. The setup screen now warns only on phones below Vulkan 1.1.

Chao keep their colours. Newborn Chao in the Chao Garden were drawn white on Android and on the Linux renderer, because two texture formats the game uses (R5G6B5 and A8) were not implemented. They are now, so Chao are light blue again, and the same textures in City Escape no longer end a session with errors. Thanks to @heyjoeway, who found and fixed this in #9. The setup screen now credits contributors.

Smaller fixes. The touch layout editor waits for the screen to turn the right way, or for split screen to end, before it lets you move the controls, so edits are no longer lost.

Downloads

Platform	Asset	Start here
Windows x86-64	OpenSA2-v0.1.0-alpha.3.1-windows-x86_64.zip	Extract the entire ZIP and run OpenSA2.cmd.
Android arm64	OpenSA2-v0.1.0-alpha.3.1-android-arm64.apk	Install the APK over the earlier one; your imported game, saves and settings stay.
Linux x86-64	OpenSA2-v0.1.0-alpha.3.1-linux-x86_64.deb	Install with sudo apt install './OpenSA2-v0.1.0-alpha.3.1-linux-x86_64.deb', then launch OpenSA2.

Setup instructions and requirements

Windows requires Windows 10 or later and a Vulkan or Direct3D 12 graphics driver. Android requires Android 10 or later, a 64-bit ARM device, and a Vulkan 1.1 or later driver. The Linux package requires Ubuntu 24.04, Debian 13, or a compatible newer distribution with Vulkan graphics.

Known problems

• The Vulkan 1.1 profile has been tested by forcing it on desktop GPUs, in an Android emulator and on a Galaxy S25 Edge, and through a test layer that makes a desktop GPU report Vulkan 1.1. It has not run on a real Vulkan 1.1 driver yet. Its picture can differ very slightly from the Vulkan 1.3 path.
• An AYN Thor stops at the SEGA logo.
• Controller remapping was tested with virtual controllers on the desktop player, not with a real controller on Android.
• Broad stage, boss, story-event and game-mode coverage is unfinished. Widescreen menus and overlays still need work.

Tested scope

With the Vulkan 1.1 profile forced, all 15,709 frames of the Metal Harbor replay match the normal path on Linux and under Wine, and the boot, menu, story and Chao Garden recordings match too. With a test layer making the GPU report Vulkan 1.1, the renderer chose the 1.1 profile by itself and matched every frame. On the Vulkan 1.3 path the shaders, device setup, reports and frames are unchanged from alpha.3. In an Android emulator the APK installed over alpha.3 with the game and settings kept, and the normal and forced 1.1 sessions both played into City Escape with every frame drawn. On a Galaxy S25 Edge, a forced 1.1 session played City Escape for about four minutes with no visible problems, and Chao World showed light-blue Chao. The Chao Garden recording no longer has the 18 texture failures and still matches DXVK on every frame. The Windows ZIP passed an isolated installation and startup under Wine, the Linux DEB passed an isolated installation and startup, and both desktop builds matched the boot replay. These checks cover the exercised paths only.

Thanks

Thanks to @heyjoeway for #9, the first outside contribution to OpenSA2: a careful fix with a clear write-up, tested on a phone. Thanks to @Gdpro835 for #5, the Adreno 610 report behind the Vulkan 1.1 profile, and to everyone sending crash reports from the app.

Source, licenses, and checksums

SHA256SUMS records the downloadable files. The project source for all three packages is at this release tag. The public source-build bootstrap remains incomplete and still needs locally generated game inputs.

Original project code is GPL-3.0-only. Packages preserve the licenses and notices for their bundled components. Original game rights remain with their respective holders. OpenSA2 is independent of SEGA and Sonic Team.

Report a problem. On Android, use the app's Report on GitHub button. Keep game files and recordings containing game data out of reports.