Secunda Launcher

Secunda is an unofficial Apple-silicon launcher for Windows Steam games you already own. Steam handles sign-in and ownership. Secunda never asks for a Steam password and never ships a game, account session, save, or Steam client.

It keeps one compatibility runtime, one private game space (a managed Windows environment for Steam and your games), and a profile for each title.

Secunda holds a game’s runtime, game space, Steam handoff, launch settings, display profile, and clean stop in one place. The software is early.

Clone the source branch, then run from source or package a local Finder app. The packaged .app, DMGs, and rebuilt Wine runtime stay in dist/ and Runtime/ on your machine; they are not committed.

git clone --branch source-only-secunda https://github.com/lukekabbash/secunda-launcher.git
cd secunda-launcher

A Finder-launchable app is produced after the source runtime exists at Runtime/wine:

./scripts/package-app.sh
open "dist/Secunda Launcher.app"

This local build is ad-hoc signed and labeled TEST-ONLY. macOS may warn on first open. Keep macOS security settings as they are until a Developer ID–signed, notarized build is available.

A ready-to-open app for tagged releases is on the Releases page.

The app creates its own private Windows prefix. Steam handles sign-in, ownership, and installation. Title status is below and in docs/source-only/GATES.md.

I have played these on my 2026 MacBook Air M5 with 24 GB of memory.

Enderal Forgotten Stories SE needs Skyrim Special Edition owned on the same Steam account.

The packaged app and Wine runtime are hundreds of megabytes and rebuild often. They remain local under dist/ and Runtime/. Generated DMGs, build caches, source archives, managed bottles, Steam data, games, saves, logs, and credentials also stay out of the repository. A future signed and notarized DMG belongs in GitHub Releases, not in commit history.

Secunda does not discover or depend on CrossOver.app. Its player path is:

Secunda.app -> source-built Wine 11.0 + packaged graphics translation -> private prefix -> Windows Steam -> selected game -> macOS graphics/audio

The current catalog contains:

• The Elder Scrolls V: Skyrim Special Edition
• Enderal: Forgotten Stories (Special Edition)
• Fallout 4
• Fallout: New Vegas
• Supreme Commander and Supreme Commander: Forged Alliance
• Supreme Commander 2
• STAR WARS Battlefront II (Classic, 2005)
• Insurgency
• Portal 2
• Half-Life 2
• Angels Fall First
• Call of Duty: Black Ops II. Campaign, Multiplayer, and Zombies

I have played Skyrim Special Edition, Fallout 4, Supreme Commander 2, and Insurgency on a 2026 MacBook Air M5 with 24 GB of memory. Insurgency is a bit laggy. The other titles are experimental. Enderal Forgotten Stories SE needs Skyrim Special Edition owned on the same Steam account.

• Apple-silicon Mac
• macOS 15 or newer
• Rosetta 2 for the x86-64 Windows worker

The Secunda interface is native arm64. Its Intel runtime workers run through Rosetta and support both 32-bit and 64-bit Windows game processes. Each catalog profile selects the packaged graphics path appropriate to that game.

If you want to run the launcher without packaging a Finder app, the supplied compliance archive must already be extracted beneath sources/, and a source runtime must exist at Runtime/wine.

./scripts/run-source.sh

There is no player-facing runtime picker. A packaged build uses only its bundled, manifest-bearing source runtime. A development run may use the repository runtime or an explicit SECUNDA_WINE_BIN, but source-only policy rejects proprietary paths and payload identities.

After building the runtime, make a Finder-launchable local app with:

./scripts/package-app.sh
open "dist/Secunda Launcher.app"

Building requires Xcode Command Line Tools plus Homebrew LLVM, LLD, Bison, CMake, and Ninja. These are build-time tools; a DMG recipient does not need them.

brew install llvm lld bison cmake ninja
./scripts/build-runtime.sh
./scripts/smoke-test-runtime.sh

The build verifies pinned inputs, applies the patches listed in packaging/runtime-provenance.json, targets macOS 15, relocates dynamic-library paths, stages notices and licenses, creates an integrity manifest, and rejects proprietary or user payloads.

./scripts/verify.sh
./scripts/test-gate-observability.sh
./scripts/verify-runtime-distribution.sh Runtime/wine

Live acceptance status and evidence are maintained in docs/source-only/GATES.md. A catalog entry or successful command is not gameplay proof: acceptance requires visible Steam, rendered gameplay, audio, keyboard/mouse input, save where supported, clean quit, relaunch, and load.

Provide the exact supplied source archive when packaging so the DMG can carry corresponding source alongside the binary runtime:

SECUNDA_SOURCE_ARCHIVE=/path/to/crossover-sources-26.3.0.tar.gz \
./scripts/package-share-dmg.sh

The output is:

• dist/Secunda Launcher-<version>.dmg
• dist/Secunda Launcher-<version>.dmg.sha256

The DMG contains Secunda, the source-built runtime, an Applications shortcut, recipient instructions, notices, an SPDX SBOM, checksums, build scripts, patches, and corresponding source. It contains no Steam client, supported-game files, prefix, credentials, sessions, saves, or logs.

For a warning-free public handoff, sign and notarize with the publisher's Apple Developer credentials:

SECUNDA_SIGNING_IDENTITY='Developer ID Application: Your Name (TEAMID)' \
SECUNDA_NOTARY_PROFILE='secunda-notary' \
SECUNDA_SOURCE_ARCHIVE=/path/to/crossover-sources-26.3.0.tar.gz \
./scripts/package-share-dmg.sh

Without those credentials the release command fails closed. For local packaging tests only, explicitly set SECUNDA_TEST_ONLY_UNNOTARIZED_DMG=1; the output is labeled TEST-ONLY, is not recipient-ready, and may show an additional first-open warning. Recipients should never be asked to disable macOS security. GitHub Actions attaches the share DMG to the matching GitHub Release when that release is published. Until Developer ID and notary credentials are present, that file is the labeled TEST-ONLY build.

All mutable player data stays beneath:

~/Library/Application Support/Secunda Launcher

That directory contains the managed Windows prefix, Steam installation/session, installed games, saves, backups, caches, and logs. Removing Secunda.app does not silently delete it; archive wanted saves before removing the managed data directory.

Runtime component licenses, notices, corresponding source, and checksums are staged by the packaging pipeline. Secunda's own launcher-code license still needs to be selected by the project owner before publishing the repository as a broadly reusable open-source project.