A shepherd counted sheep by sight, we count cells
A shepherd climbed a stone and swept his eyes across the flock. So many sheep left, so many right, then the hill cuts the view. Corral is the same stone, with cells instead of sheep.
My grandfather kept sheep all his life, and the thought is his. He used to say: build the pen so the flock stays one piece from any spot. A cut-off pocket is a gift to the wolf. Corral keeps the rule: all empty cells join into one connected pen. Fence off a pocket and the solve is broken, even if the numbers add up.
Numbers see until the first wall
Each number counts empty cells horizontally and vertically until the first shaded cell or the grid edge. Wall nearby, short sight. Wall gone, the number sees far. I start with edge numbers: the border squeezes their sight, so options are few. "New" deals a fresh grid, "Hint" shades one correct cell, "Reset" clears everything.
The funny part: the numbers never count walls. They count emptiness. The eye wants to hunt cells to shade, while the game asks you to watch what stays white. Flip the gaze and the solve moves. Keep hunting and you hit a wall.
Grandfather would have said: first watch where the sheep walk, then raise the fence.