Screw and Bolt Sort: 7 Techniques to Clear the Hardest Levels

Screw-and-bolt sort games are the tightest-designed puzzles in the sorting genre. Where water sort gives you generous empty-tube counts and ball sort gives you multiple paths to the same solution, screw-and-bolt levels are usually balanced on a knife edge. One wrong tap and the level is a restart. One right tap and the whole thing collapses into place.

This article is for players who have already cleared the first 50 levels of any screw-and-bolt game and are now running into walls. Seven techniques, in the order you should learn them.

1. Empty rod economy

An empty rod is worth more than any single coloured nut. Never fill an empty rod unless the move directly finishes a colour or creates a better empty rod elsewhere. This is the same empty-slot rule that water sort players already know, but screw-and-bolt is much less forgiving of mistakes — you usually only get one or two empty rods in the mid-game, and losing both means restart.

2. Priority colours

Before your first unscrew, look across every rod and find the colour with the largest already-stacked block. That is your priority colour. Finish it first. Do not get distracted by the chaos of the other rods — clean the one thing that is nearly done, reclaim its rod, and use that new empty rod for the rest of the solve.

3. The setup move

A "setup move" is a move that does not finish anything by itself but makes the next move possible. Screw-and-bolt puzzles are almost entirely setup moves — the satisfying cleanup only comes at the end. If you are only making moves that directly clean up, you are missing the entire strategic layer of the genre.

Practical example: you can see that moving a green nut from rod A to rod B would not finish anything. But moving it reveals a red nut underneath, which you can then move to rod C, which finishes the red colour. That first green-to-B move is the setup; it only makes sense when you plan it as a pair.

4. Two-move planning, minimum

Screw-and-bolt punishes single-move thinking more harshly than any other sorting subgenre. Before every tap, have at least two moves in your head. If the next two moves are obvious and good, tap. If you can only see one move clearly, pause longer.

5. Never stack a unique colour onto a mixed rod

If there is only one of a particular colour on the entire board, do not put it on a mixed rod. You will need that colour to complete its destination later, and every move you make in the meantime has to work around keeping it accessible. Unique colours go on empty rods or matching rods — never into the general mess.

6. When to restart: the "blocked unique" signal

The single clearest signal that a level is unwinnable from your current state is when a unique colour has been buried under two or more mismatched nuts. Once that happens, freeing the unique colour will cost you more moves than you have budget for, and the level is essentially over. Restart immediately — trying to rescue a blocked-unique situation almost always wastes more time than a clean restart would.

7. The "last move test"

Before each tap, imagine the level almost-finished: one rod left to clean, one empty rod in reserve. Does the move you are about to make lead to that endgame state? If yes, it is probably right. If you cannot picture how this move fits into the final position, it is almost certainly a wasted tap.

This is the same technique chess players call "visualising the endgame", and it works identically well in screw-and-bolt sort because both games have deterministic solutions.

Where to practise

The Screw & Bolt Sort category on SortFun collects the genre's best current titles. If you have already cleared the easy ones and are looking for something that will genuinely challenge these seven techniques, the later games in that list ramp up noticeably around level 60 and do not let up. Good luck.