* Hold shift to use pencil temporarily, double tap to switch. - Optionally use Caps Lock to switch (activate via control panel).
* Use Alt-P (Option-P) to pause/unpause the timer.
* Activate dark mode from the puzzle's control panel (gear icon). Preserves yellow and blue highlights, and keeps shaded squares visible, while saving your eyes.
* Activate red pencil from the control panel, to make pencil stand out.
