SnowFall

Interactive snow for your desktop. Snowflakes settle on the top edges of your windows and the taskbar, build up into drifts and travel with the windows. Brush the snow away, scoop and fling it with a shovel, roll snowballs, throw them at windows, and build snowmen — by hand or by stacking balls. A toy snowplow clears the taskbar when it gets buried.

Platforms: Windows 11 x64 (native C++20, Win32 + Direct3D 11) and, as a first test build, macOS 13+ (Objective-C++, Metal, SwiftUI; Apple Silicon and Intel) — see platform/macos. Русская версия README

Features

• Snow that lives on your desktop: drifts on window tops, the taskbar and the screen bottom, hidden behind overlapping windows, carried along when a window moves, shaken off in chunks when you jerk a window, lumpy natural caps, icicles under long-lying snow.
• Weather: Light, Normal, Blizzard and Thaw (wet snow, melting drifts, dripping icicles), wind and gusts, snow that flows around the mouse pointer like under an umbrella.
• Tools (hold Ctrl+Alt or the shown chord, or toggle interaction mode):
  • Snowball — roll a ball out of a drift, throw it (it splats on windows), stack balls into snowmen;
  • Mitten — press and hold on a drift to sculpt a snowman; a quick swipe brushes snow away;
  • Shovel — scoop snow and fling it; it lands as a new mound; knocks snowmen over.
• Snowmen with 12 skins (Santa, pirate, DJ, king, kitty…), falling from the sky during heavy snow (configurable), falling apart realistically when plowed or shoveled.
• Festive extras: taskbar garland, New Year's midnight fireworks (or any time on demand).
• Three settings themes with a live preview, a quick panel next to the tray icon, user presets, per-application exclusions (snow passes behind or flows around their windows).
• Lightweight and private: about 0.2–0.5 % CPU, ~35 MB RAM, auto-pause for fullscreen apps, locked sessions and sleep. No telemetry, no reading of other windows' contents, no injection, no admin rights. The only network use is the optional update check (asked once): one request a day to the GitHub Releases API with nothing about you; updates are installed only from signed releases.

Quick panel	Snowman skins

"Snow globe" theme	"New Year card" theme

Install

Download SnowFallSetup.exe from Releases (per-user install, no admin rights; uninstall from Settings → Apps), or the portable zip.

Builds are not code-signed yet, so Windows SmartScreen may warn on first launch.

macOS: download SnowFall-<version>.dmg and drag SnowFall to Applications. The app is not notarized, so macOS refuses the first launch ("could not be verified" or "is damaged"). Either run

xattr -cr /Applications/SnowFall.app

or click "Done", then System Settings → Privacy & Security → "Open Anyway". Clicking the snow needs the Accessibility permission (the app asks the first time you hold Ctrl+Option).

Build from source

Requirements: Visual Studio 2022 Build Tools (MSVC x64, Windows SDK 10.0.22621+), CMake ≥ 3.24, Ninja.

build.bat build Release          :: everything into build\
build\SnowFall.exe               :: run

Packaging: platform\windows\packaging\make_portable.bat (zip), platform\windows\packaging\make_msix.bat (unsigned MSIX); the installer SnowFallSetup.exe is built together with the app. See platform/windows/packaging.

Tests

Command (in build\)	What it covers
snow_sim_tests	physics, drifts, occlusion, tools, snowmen, snowplow, festive effects, benchmark
snow_settings_tests, snow_settings_win_tests	JSON, migrations, ranges, presets, hotkeys, file I/O, autostart
tracker_dump --selftest	window tracking on real windows: Z-order, minimize, fullscreen, coalescing
render_demo --selftest	transparency, click-through, frame pacing, device-loss recovery, clipping
ui_demo --selftest	tray, quick panel and settings window in all themes, RU/EN, 100–200 % DPI
e2e_smoke <SnowFall.exe>	the real app end to end: snow settles, moves with a window, clears, exits cleanly
soak_test --minutes 480	long run: memory, handles, CPU, hangs

Tests read screen pixels only inside their own test windows.

Repository layout

core/               portable C++20: simulation, drifts, tools, snowmen, settings model (no OS headers)
platform/windows/   Win32 app, D3D11 overlay renderer, window tracker, UI, installer, packaging
platform/macos/     macOS app: Metal overlay, window tracker, SwiftUI settings (test build)
docs/               architecture, test plan, screenshots

Details: docs/architecture.md · docs/development.md.

License

SnowFall is source-available under the PolyForm Noncommercial License 1.0.0: you may use, study, modify and share it for personal and other noncommercial purposes. Commercial use requires a separate license — contact the author via GitHub or Telegram.

Contributions are welcome under the terms in CONTRIBUTING.md.

SnowFall is an independent project and is not affiliated with any other desktop-snow product.