kageroumado Releases Sevoflurane Beta for Windows Steam Games on Apple Silicon Macs

On September 30, 2026, kageroumado released the first public beta of Sevoflurane, a free and open-source application that plays Windows Steam games on Macs with Apple silicon. Sevoflurane integrates Steam and compatible games with native windows, menus, notifications and Dock icons.

The Windows Steam client runs hidden inside Wine. Sevoflurane opens Steam's web-based interface in native WebKit windows at full Retina resolution and connects them to the client, so the library, store, friends list, chats and the in-game overlay each appear as a Mac window, with Steam's menus in the macOS menu bar and its alerts delivered as Mac notifications.

Games launch through individual Mac application wrappers with its own name and Dock icon, which allows macOS to engage Game Mode automatically when the game fills the screen. Supported games with a fixed window size can use resizable windows and native full screen while retaining their original rendering resolution. Optional upscaling renders the picture beyond the game's own resolution, using Lanczos filtering by default, Apple's MetalFX for 3D games, and Anime4K and CuNNy shaders for visual novels and 2D art.

Games run on Dormison, kageroumado's Wine fork based on upstream Wine and wine-staging. Its changes include a presentation-time upscaler for Metal, OpenGL and GDI windows, and resizable windows that preserve the game's rendering resolution. DirectX 12 support uses D3DMetal from Apple's Game Porting Toolkit. Compatibility depends on the game, Mac and graphics translator. CrossOver is also supported as an engine. Windows programs outside Steam open directly from Finder, and HoYoverse titles including Genshin Impact, Honkai: Star Rail and Zenless Zone Zero install and update from HoYoverse's own servers.

On October 8, 2026, kageroumado released Sevoflurane 1.1 beta 1 with the Dormison b2 engine. Steam's library now shows each game's Mac compatibility verdict from players' recorded runs, with a filter for the games that play, and asks before installing a game whose anti-cheat cannot run on a Mac. Games Steam sells for macOS can play their native version through Valve's Steam for Mac. A game's first launch applies the settings other players found it needs, from a signed community fix list, with an undo, and launch options written for Valve's Proton work unchanged. The update also adds a frame-rate limiter and a performance overlay, Windows programs' menus in the macOS menu bar, controller support with the SDL input bus off, hardware HEVC video decoding, and a Steam-style Dock menu.

On October 10, 2026, kageroumado released Sevoflurane 1.4 and 1.5 with the Dormison r5 and r6 engines, ending the beta: every version is now a regular release. Sevoflurane's own Steam now installs and plays a game's native macOS version when Steam sells one. Installing such a game asks which version to download, with each version's size and compatibility rating, and the play bar switches an installed game between its macOS and Windows versions. The macOS version runs natively and reaches the Steam client through a bridge, so achievements, stats and cloud saves work without Valve's Steam for Mac, which remains an option.

Key features

• Steam's library, store, friends and chats in native Retina Mac windows
• Per-game Mac application wrappers with Dock icons and Game Mode integration
• Resizable windows and native full screen for supported fixed-size games
• Optional upscaling: Lanczos, MetalFX, Anime4K and CuNNy
• DirectX 12 via D3DMetal on the Dormison Wine engine
• Mac compatibility verdicts and a Mac filter in Steam's library
• Native macOS versions installed and played from the same Steam, switchable per game
• A signed community fix list applied at a game's first launch, with an undo

How it compares

Availability

Sevoflurane 1.5 is available now as a free download from kagerou.glass/sevoflurane and GitHub. It requires macOS 26 or later on a Mac with Apple silicon. The source code is published under the MIT License.