You will not be racing anything here: there is no timer, no cap on moves and no way to lose a board. What you have instead is a row of threaded bolts against a dark backdrop, crowded with colored hex nuts in the wrong order, one bolt left bare, and all the time you want to study them before the first touch.
Only the top nut of a stack ever moves, and only one at a time. Lift it from one bolt and set it on another, as long as the destination is empty or already topped with the same color and still has room, because a bolt holds four nuts and no more. A board is solved when every bolt carrying nuts carries four of a single color. The first three levels use three colors across five bolts, a fourth color and a sixth bolt arrive at level four, and levels eleven to twenty spread five colors over seven bolts, with no bolt starting out already sorted.
Twenty boards open in order, from a ten-move shortest solution on the first to twenty-two on the last. Match that number and the board earns three stars, stay within a few moves of it for two, and any finish still earns one. Each level keeps its best star rating and its lowest move count separately, and cleared boards stay open for another try at the shorter route. Undo steps back through every move of the attempt and takes the counter back with it, a restart returns the exact opening layout, and a hint marks which bolt to take from and which to drop on, worked out from the position in front of you, without making the move for you. Hints can be switched off, sound, music and vibration each have their own setting, an illustrated three-step guide covers the rules, and a half-finished board is stored offline on the phone, undo history included and without any account behind it, so it comes back exactly as you left it.
The last board's shortest solution is twenty-two moves, and its third star goes only to a finish that matches it.
Move colored hex nuts one at a time until every bolt holds four of a kind