Hard and tricky.
Great Permutator is a puzzle.
Features
50 levels (+15 bonus levels)
10+ types of action blocks
16 not-so-easy achievements
Global score leaderboard
Nice pixel art graphics and cool soundtrack
Level editor with sharing levels via Internet
One in which you will have to build a complex system of conveyors and various devices so that the colored boxes can travel across the factory and arrive at right places and in right order. Great Permutator. If you are into clever engineering puzzles like LightBot, Manufactoria and SpaceChem, this game is for you.