How to get three stars on every timed level

A solver looks at a Quick 4x4 board with one empty cell left in the top row. The tray holds a 3, and it fits in two of the columns. Taps on the nearer column send the number down to the lowest empty cell, and the level ends in a very short time. Even though one earlier drop was wrong, that one mistake holds the level at two stars.

NumFall levels are timed, and the third star goes to a solver who finishes fast with no mistakes. A quick finish with one wrong drop is not enough to earn it. Both numbers matter on every level, since a slower, clean finish may not earn it either.

The boards come in three sizes: Quick 4x4, Classic 6x6 and Master 9x9. Named sets of ten group the levels, and each level's flames show how hard it is. Solvers usually read the flames first, then look at the board.

Read the drop order before the clock starts

Before the clock starts, solvers usually scan the board in a fixed order: each row, then each column, then each box. On a 4x4 board the boxes are the four 2x2 blocks. Solvers also note which numbers are missing from each row, column and box, and which tray numbers fit in more than one column.

The lowest empty cell in the chosen column takes each falling number, so every drop fills a cell that later numbers can no longer use. A number that fits two columns can go into either one, but the choice changes what the other tray numbers can do later.

Picture a 4x4 board with three empty cells in the left column, two in the right, and a 2 and a 4 in the tray. The solver writes out Order A, the 2 in the left column first, then the 4. Order B has the 4 dropped first, followed by the 2. After each paper drop, the solver crosses off the numbers that no longer fit anywhere. Order B is the one to play when Order A leaves four open cells that still accept a number and Order B leaves two.

In many falling block puzzles, a single merge can set off a chain. After a merge, the new block may touch another block of the same new value and merge again. Those games let players place one block per move while the rest of the board stays still, so each placement can be checked for what it sets off.

Count mistakes before counting seconds

Before each drop, solvers usually check the chosen number against three places: the row it will land in, the column it falls into, and the 2x2 box on a 4x4 board. The number lands in the lowest empty cell of the column, so the check is made for that cell and not for the top of the column. One mistake removes the three-star result for the level, however fast the finish.

Many solvers write a running count for each level on paper or in a notes app. For that attempt, a level that starts at zero and ends at one counts as a two-star level, and the note records which drop caused the mistake. Across several levels, the notes reveal whether mistakes come mostly from rows, columns or boxes.

Undos, hints and an extra heart are paid for with sparks. Since sparks cannot be bought and come only from play, a solver can spend them without paying money. Using a hint or undo does not restore a clean count for the level.

Every level can be solved by logic alone, with no guessing. A solver who checks each placement slowly can still finish, and those extra seconds cost less than a mistake.

Pace each set of ten with a time to beat

A solver working through a named set of ten can keep a small table, with one row per level, for the time and the mistake count. After level one, the solver sees a time of, say, 58 seconds and one mistake. The next attempt at that level aims for a few seconds under the last result, perhaps 52 seconds.

Every level has its own goal. A level finished in 40 seconds with no mistakes may already have the third star, but the same 40 seconds with one mistake still needs a clean replay. When looking at results, solvers check the mistake column first and then the time column.

After all ten levels are played, the solver replays any level that missed the third star before moving to the next set. The new result replaces the old one in the table, and each replay has its goal written beside it.

Master 9x9 levels are usually saved until a solver is steady on Classic 6x6. A 9x9 board has nine rows, nine columns and nine boxes to check before each drop, so the habits from the smaller boards need to be in place first.

NumFall is free on iPhone and iPad and can be found on NumFall on the App Store for players who want to try a set.

NumFall is made by the publisher of this site. Any health or brain-training points here are general information, not medical advice.