Two surveillance frames of the same scene — taken minutes apart through a night vision scope. Something has changed. Click every difference you can spot on either image. You'll be scored on detection accuracy and shown the tactical significance of each change.

Click anywhere on either image where you spot a difference. Correct clicks mark both scenes with a green ring. If you get stuck, use the Hint button — an arrow will point to one remaining difference for 3 seconds, but counts as a miss.