4×4 CHANGE HUNT · 15 ROUNDS
Memorize the pixel pattern, then find the one cell that changed.
Complete 15 rounds. Wrong answers and timeouts count, then the test continues.
READY?
Study all 16 symbols. After the mask, choose the cell that looks different.
Keyboard: 1–9, then A–G · Touch or mouse: select any cell
HOW TO PLAY
Study the full 4×4 pixel pattern. This memory phase lasts about 800 milliseconds and is not part of your reaction time.
A brief mask hides the board while exactly one cell changes its symbol, shape, or texture.
When the changed board returns, the timing bar starts. Tap the changed cell or press its displayed 1–9 / A–G key.
VISUAL MEMORY
You encode several visual details, hold the scene through a short interruption, and compare it with a second view. That combines visual working memory, comparison, and choice reaction.
Changes never depend on color alone. Symbols, outlines, fills, and textures provide additional visual cues.
READ YOUR RESULT
Reaction time begins only after the changed grid is visible. Average and best times use correct answers; accuracy includes wrong answers and timeouts.
Endless mode gives one life. Its study phase shortens, answer window falls from 4.0 seconds toward 1.0 second, and later changes are more similar.
QUESTIONS
The reaction timer and timing bar start when the changed grid appears. Studying the original pattern and waiting through the mask are not included.
Read left to right, top to bottom: the first nine cells use 1 through 9, and the final seven use A through G. Every cell displays its own key.
Standard mode records the wrong answer or timeout and continues until round 15. Endless mode ends on the first mistake.
Color is decorative rather than the only clue. The changed cell also differs in symbol, fill, outline, or texture.
Yes. Tap the changed cell directly. The 4×4 grid scales down for narrow screens without horizontal scrolling.