OpenSA2 0.1.0-alpha.2

Important

A newer version is out: OpenSA2 0.1.0-alpha.6.1. It has volume sliders for the music, voices and sound effects, 68 optional tweaks, a Chao World button, a fix for the crash after a Chao race, and many fixes. On Android, install it over this one; your imported game and saves stay. Every version is listed on the releases page.

Updated 2026-10-17: all three packages were replaced with 0.1.0-alpha.2.1. Story movies now play. Before this update they stayed black and silent and never ended, starting with the Prison Island movie after Green Forest, because the movie decoder needed a function the port had not translated. Install the APK over the earlier one, or replace your Windows or Linux install; your imported game and saves stay. The Android app also keeps a crash report when a frozen game has to be closed, names crashes in the report, and keeps the setup screen clear of the status bar.

OpenSA2's second experimental prerelease adds crash reports to the Android app, explains refused installs in plain words, and brings the October 15 crash fixes to Windows and Linux.

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

Crash reports on Android. If the game stops, OpenSA2 returns to its setup screen and says what happened. Tap Report on GitHub: the app copies a crash report and opens the bug-report form with your device filled in, so you only paste the report and describe what you were doing. Copy summary gives a shorter version that fits in a forum comment. The report holds the device, the GPU and its driver, how the session ended, the game's trap or the renderer's failure, and the game's last log lines. It holds no game files or account details.

Clearer setup. When the installer refuses your files, the setup screen now says why and how to fix it: a modified or non-Steam sonic2app.exe, missing or changed files, files added by mods, a ZIP without the game, and so on. A timer shows that the check is still running. A phone whose graphics driver reports a Vulkan version older than 1.3 gets a warning before it imports anything.

Version in the app. The setup screen's title shows the version, so a bug report can name the build.

Desktop fixes. The Windows and Linux packages now include the two crash fixes the Android APK received on October 15: the stop at the event after a stage (the CRT _CItan trap) and the mid-stage stop in Dry Lagoon.

Downloads

Platform	Asset	Start here
Windows x86-64	OpenSA2-v0.1.0-alpha.2-windows-x86_64.zip	Extract the entire ZIP and run OpenSA2.cmd.
Android arm64	OpenSA2-v0.1.0-alpha.2-android-arm64.apk	Install the APK over the earlier one; your imported game stays.
Linux x86-64	OpenSA2-v0.1.0-alpha.2-linux-x86_64.deb	Install with sudo apt install './OpenSA2-v0.1.0-alpha.2-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 1.3 driver. The Linux package requires Ubuntu 24.04, Debian 13, or a compatible newer distribution with Vulkan graphics.

Known problems

• Phones whose graphics driver offers only Vulkan 1.1, such as one with an Adreno 610, can't start the renderer yet; the setup screen warns about this. Some phones show a black picture with sound and touch controls, and an AYN Thor stops at the SEGA logo. Crash reports from this build help with both.
• Broad stage, boss, story-event and game-mode coverage is unfinished. Widescreen menus and overlays still need work.

Tested scope

The Android APK passed installation over alpha.1, a clean session, crash reports for a native crash, a game crash and a hung game, the installer's refusal of a modified game folder, and the GitHub form link in an Android emulator, and a session on a Galaxy S25 Edge. The Windows ZIP passed an isolated installation and startup under Wine. The Linux DEB passed an isolated installation and startup. Both desktop builds matched the boot replay. The 0.1.0-alpha.2.1 APK played the Prison Island movie through to Pumpkin Hill, skipped it with Start, and kept its crash reports for a frozen game in an Android emulator; the same fix played that movie, two later Hero movies and a Start skip on Linux. The 0.1.0-alpha.2.1 Windows ZIP and Linux DEB passed the same isolated installation and startup tests and matched the boot replay. These checks cover the exercised paths only.

Thanks

Thanks to everyone who reported problems with the first prerelease: @rsomethin (#1, the crash after Green Forest), @pcddlXDDD (#3, a crash at startup), and on Reddit u/lepoyoperry (the Knuckles stage crash and the black screen after it), u/APMichaels (the freeze at the SEGA logo), u/No_Cod_4703 (a black screen at startup), u/Demnetor42 (setup trouble that led to the clearer instructions) and u/Away_Glass_8061 (the ZIP import problem fixed during alpha.1).

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.