Bottom line: Game Mode is a shared viewport state that gives the board more room by hiding page chrome. The game viewport fills the screen (fullscreen when the browser allows it, otherwise a “Focus mode” fallback), the toolbar collapses into an icon bar, and Escape or the toolbar exit returns to the normal page.
How to enter and exit
- Enter: the toolbar’s “Focus mode” button (desktop) or the Game Mode entry in Game settings (mobile compact toolbar).
- Exit: Escape, or the exit control that leads the toolbar in Game Mode so it is the first thing a thumb reaches.
- Fallback: when the Fullscreen API is unavailable or denied, NoCharge’s immersive fallback fills the viewport with the same compact chrome.
What changes
- Page header, footer, related content, and ads are out of view.
- The toolbar becomes a single icon bar; Pause, Mute, Settings, and Exit remain in the same Document order (icon‑only visually, full accessible names).
- The status line moves below the stage instead of pushing the board down.
What does not change
- Game rules, difficulty, modes, and saved state.
- Keyboard focus order and accessible names.
- Pause-on-hidden behavior: audio still stops and the game pauses when the page hides.
Limits
Game Mode is a viewport improvement, not a performance boost or a networking feature. It does not change device rendering; a heavy board still depends on the device’s browser and hardware. NoCharge does not claim a measurable frame-rate improvement.