CENTER JUDGMENT · 24 ROUNDS
Decide whether the gold marker sits left or right of the line's true midpoint.
Play 24 rounds with exactly 12 LEFT and 12 RIGHT answers. The offset gradually shrinks; mistakes continue.
READY?
The line is always perfectly symmetric. Only the marker moves.
Keyboard: A or ← chooses LEFT · L or → chooses RIGHT · Touch or mouse: use the two large buttons.
HOW TO PLAY
Look at the full horizontal line. Its two endpoint caps are identical and stay fixed.
Estimate the exact halfway point without a visible center tick.
Choose whether the gold marker is LEFT or RIGHT of that midpoint before time expires.
SPATIAL ESTIMATION
The line remains centered, horizontal, and visually identical in every round. Both end caps use the same size, color, and shape.
Only the gold marker changes position. Standard mode gradually reduces its distance from the true midpoint while balancing both sides.
ENTERTAINMENT CHALLENGE
This game is for entertainment and personal practice. It is not a clinical visual, neurological, or spatial-neglect assessment.
Screen size, display scaling, viewing distance, input latency, and practice can affect your result.
QUESTIONS
Yes. Its position, length, thickness, color, and two endpoint caps remain identical. There is no center tick.
Yes. Standard mode contains exactly 12 LEFT and 12 RIGHT marker positions in shuffled order.
The marker moves progressively closer to the midpoint. Endless mode also shortens the answer window after correct judgments.
No. This recreational browser game does not diagnose vision, attention, or neurological conditions.