SANDSHIFT

SANDSHIFT is a portrait-first color-flow puzzle inspired by physical pixel-sand sorting. Tap the open bucket at the front of one of four queues. Active buckets ride a six-slot looping conveyor and collect matching bottom pixels only while those pixels are inside the bucket's four-cell overhead window. After a lower pixel is collected, every pixel above it in that column falls down in order. Three normal buckets of one color merge into a deep bucket and compress three tray slots into one.