Steamac — Kiwi Build

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A personal fork of fxgl/steamac, focused on quality-of-life improvements for running SteamOS games on Apple silicon Macs.

The current release is based on Steamac 1.9 and brings all upstream improvements from releases 1.8, 1.8.1, 1.8.2, and 1.9 alongside Kiwi enhancements (75% automatic RAM allocation, BepisBridge, Discord Rich Presence, GE-Proton installer, and ReShade/Asset Mod management).

Latest Kiwi release: v1.9-kiwi.1 (download)

Kiwi Build 1.9 pairs with BepisLoader 2.3.4+ for mod management and SteamOS integration.

New in Kiwi Build 1.9 (v1.9-kiwi.1)

Upstream 1.8 – 1.9 Features Integrated

• DirectX 12 Feature Level 12_0 on KosmicKrisp (macOS 26+):
  • Implements real tiled resources (D3D12 tiled resources tier 2) on Metal 4 placement sparse resources: sparse binding of images and buffers, shader residency queries (CheckAccessFullyMapped), unbound tiles reading zero, and sampler min/max reduction.
  • Enables DirectX 12 games that strictly require feature level 12_0 (such as Resident Evil 2) to launch and access enhanced rendering paths.
• Multichannel Audio up to 12 Channels:
  • Automatically reads speaker layouts configured in macOS Audio MIDI Setup at VM boot (supporting 5.1, 7.1, 5.1.2, and 7.1.4 with height speakers).
  • Routes PCM channels directly to physical hardware speakers with automatic downmixing when physical channels are missing.
• Instant Output Switching:
  • Audio follows default output changes (such as connecting AirPods or selecting a device in macOS Control Center) immediately without lag.
• Multiplayer Controller Support:
  • Additional connected gamepads beyond the primary controller automatically map to guest player slots 2–4.
• MoltenVK & DXVK Compatibility Fixes:
  • Counter-Strike 2: Empty/null descriptor sets bound via vkCmdBindDescriptorSets no longer crash the VM.
  • Left 4 Dead 2 & DXVK: Fragment shaders writing unsigned values to signed-integer render targets now compile correctly without shader errors.
• KosmicKrisp Stability & Diagnostics:
  • Dota 2 & CS2: Query pool exhaustion resolved by chunking occlusion results and sharing timestamp counter heaps.
  • M3+ GPU Startup Fix: Render pass target textures are registered in Metal 4 residency sets, resolving startup GPU timeouts.
  • Detailed diagnostic reporting naming the exact GPU workload and driver failure reason on timeouts.
• Clearer Network & Certificate Errors:
  • VPN, proxy, and TLS issues provide actionable diagnostic messages rather than raw system error codes.
  • Valve development-signed builds (e.g., rc branch) are identified clearly with fallback suggestions.
• Metal Compiler Cache Fallback:
  • Automatically redirects to launcher cache if app compiler cache directories are read-only.
• UI Localization:
  • Launcher windows, menus, settings, and progress notifications now support Russian and Simplified Chinese based on system language preferences.

Maintained Kiwi Enhancements

• 75% Automatic VM Memory Allocation: Retains generous host memory sizing (up to 75% of physical RAM, 4–16 GiB) while reserving adequate memory for macOS and unified GPU workloads.
• BepisBridge Integration: Seamless integration with BepisLoader for mod installation, ReShade injection, and game library inspection.
• Discord Rich Presence: Native macOS Discord IPC status updates with active game art and playtime tracking.
• GE-Proton Runtime Downloader: One-click GE-Proton installation into SteamOS compatibility tools directly from Settings.
• Combined Asset Mod Profiles & ReShade: Full support for checked asset replacement, MBE CSV tables, ADX2 audio banks, and DXGI ReShade runtime injection.

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What's different in the Kiwi Build?

More automatic VM memory

The Kiwi Build increases Steamac's automatic VM memory allocation from 50% to 75% of host RAM, while retaining the existing 4 GiB minimum and 16 GiB maximum.

Typical automatic allocations:

Mac RAM	SteamOS VM
8 GB	6 GiB
16 GB	12 GiB
18 GB	~14 GiB
24 GB+	16 GiB

This gives memory-hungry games more room inside SteamOS while still reserving memory for macOS and shared GPU resources. You can still override the automatic value manually in Settings.

Kiwi Build updater

The built-in update checker follows releases from this fork (KiwiSingh/steamac) rather than upstream. Release tags use the vX.Y.Z-kiwi.N format (e.g. v1.9-kiwi.1).

BepisBridge integration

Kiwi Build includes BepisBridge setup in Settings to support integration with BepisLoader. The setup provisions per-VM SSH authentication and virtio communication, enabling BepisLoader to interact directly with the running SteamOS guest.

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Download

Prebuilt Kiwi releases are available from:

https://github.com/KiwiSingh/steamac/releases

The current release is:

Steamac 1.9 Kiwi Build 1 — v1.9-kiwi.1

The release ZIP is ad-hoc signed and is not notarized with an Apple Developer ID.

Building

This fork follows the upstream Steamac build system. Refer to the source tree and upstream documentation for build requirements and instructions.

The Kiwi-specific changes are intentionally kept small and isolated from upstream functionality.

Upstream

Steamac is developed by fxgl:

https://github.com/fxgl/steamac

This fork tracks the upstream project and adds Kiwi-specific changes on top. Features that are subsequently implemented or superseded upstream defer to the upstream implementation rather than maintain unnecessary parallel code.

License

See the repository's existing license and upstream Steamac licensing information.