Brain Test: IQ Challenge

Level 128 of this game asks you to light a candle. There is a candle, there is a matchbox, and clicking the matchbox does nothing. The solution is to pinch the matchbox until it is large enough that the matches inside become objects you can pick up. You have to stop seeing a picture of a box and start seeing a container.

That puzzle is roughly eighty years old. In 1945 the American Psychological Association published a monograph by a German psychologist named Karl Duncker built around almost exactly this setup — a candle, a box of matches, a box of tacks — and the thing it measured has a name. This game is a 252-level tour of it.

First, the awkward part, because the name on the tin is misleading. This is not Unico Studio's Brain Test. The game with a hundred million downloads and 9.92 million reviews is Brain Test: Tricky Puzzles, by Unico Studio LLC of Palo Alto, California. This one still calls itself Brain Crazy in its own data file, began as an Android app in 2021, and reached GameMonetize in January 2026 under a publisher account named Lodestone. If you came for the famous one, this is not it. If you came for 252 free trick riddles in a browser tab, this is a real one.

Everything above is checkable, and it was checked. The Unity data file was downloaded, decompressed and opened; inside it sits a localisation table of 816 rows in 16 languages. That table is where the level count, the hint text and the language list on this page come from. No store description was trusted for any of it.

The trick has a name, and a number: functional fixedness

Functional fixedness is the inability to see an object as anything other than what it is usually for. The term is Duncker's, and his own definition was blunt: a mental block against using an object in a new way.

He demonstrated it with what he called the box problem, now known as the candle problem. Participants sat at a table with a candle, a box of matches and a box of thumbtacks, and had to fix the candle to the wall so that it would not drip. The solution is to empty a box, tack the empty box to the wall and stand the candle in it. Only 43 per cent of Duncker's participants got there. Given the same objects with the boxes already empty, a control group solved it 100 per cent of the time. Nothing changed except whether the box was currently doing its job.

Duncker did not live to see the paper. Born in Leipzig in 1903, he worked in Berlin alongside the founders of Gestalt psychology, left Germany in 1935 and died in the United States in 1940, aged thirty-seven; On problem-solving appeared posthumously in 1945. The finding has held up in odd ways since. Sam Glucksberg showed in 1962 that offering people money to solve the candle problem made them on average three and a half minutes slower — take the tacks out of the box first, and the same cash incentive helped instead.

Now look at what this game asks of you. The screen border stops being a frame and becomes a wall you can push things past. The question stops being an instruction and becomes a plank. The phone stops being a display and becomes a box you can tip up. Every one of those is a matchbox that has to stop being a matchbox — the same move, repeated 252 times.

What is actually in the 252 levels

Counted from the hint text, the tricks break down like this:

The move	Levels	A real example
Shake or flip the device	13	Level 40 asks how many coconuts there are, and hides some in the palm leaves until you shake the tree
Pinch to zoom in or out	19	Level 69 asks how the cat beats the mouse: make the mouse bigger and it loses
Use the question text or level number	14	Level 200 asks where Vietnam is, and the answer is the word in the question
Drag something past the screen edge	9	Level 9 wakes the owl by dragging the sun off the screen
Two touches at once	4	Level 173 tells you to cut the red cord or the blue one, and means both

The rest is genre furniture: about fifty find-the-thing levels, twenty-one counting questions with something hidden, nineteen rescues, seventeen arithmetic puzzles with a lie in them, and a handful wanting taps in a set order. Several late levels are stock riddles rather than scenes — "How many months have 28 days", "Mary's father has five daughters, namely Nana, Nene, Nini, Nono, so what is the fifth daughter's name" — a fair sign the design ran out of ideas before it ran out of slots.

One honest warning about desktop. The thirteen motion levels read the browser's devicemotion event, which a desktop browser never fires, and nothing on screen says so. If a level wants something you cannot give it, that is probably one of the thirteen, and 2 keys moves you past. On a phone they work as designed. This is a mobile game wearing a browser page, and the 350×600 portrait frame shows it as plainly as the controls do.

Why "IQ Challenge" is not an IQ test

Half the puzzle games on the web have "IQ" in the title, and none of them are measuring one.

An IQ score is not a count of right answers. It is a rank. Your raw score is compared against a representative standardisation sample of people your own age, then placed on a scale deliberately set to a mean of 100 and a standard deviation of 15 — which puts roughly two thirds of the population between 85 and 115, and about 2 per cent above 130. Without the sample there is no score, only a tally.

The non-verbal test these games imitate is usually Raven's Progressive Matrices, a pattern-completion test with retest reliability around 0.80 to 0.90. Even that has to be re-normed regularly, because scores drift upward across generations at roughly three points per decade — the Flynn effect.

And one result settles the question outright. A 2018 meta-analysis by Scharfen, Peters and Holling found that simply sitting a cognitive test a second time raises the score by about a third of a standard deviation, roughly five IQ points, with a further jump by the third sitting — and the effect is about twice as large when the test is identical rather than a parallel version, because you remember the items. Practising test-shaped questions moves the number without moving anything underneath it.

None of which makes the game worthless. Insight puzzles are worth doing, and Duncker's whole point was that the block is real and beatable. It just is not a measurement.

Playing it unblocked at school

There is no plugin, no installer and no login here — one Unity WebGL page, so it runs on a school Chromebook as readily as anywhere else, which is why "brain test unblocked" is the search that brings most people to games like this one.

The catch is size: 35 MB to download before level 1 appears, and about 50 MB once decompressed. On shared school wifi that is a long wait on a Unity logo. And because progress lives in browser storage rather than an account, clearing site data drops you back to level 1 with 35 keys.

More puzzle games

If it was the lateral thinking you came for rather than the branding, the same "the obvious move is wrong" design runs through Hero Rescue Puzzle and Pull Him Out Online, where you pull pins in an order and the wrong order drowns somebody. Hero Rescue is the faster, action-flavoured version of that, and Kingdom Tower Defense trades riddles for the slower kind of thinking ahead. The full shelf is in the puzzle category.

1. Read the question, then distrust it. Level 1 says "Find the Longest one" and puts a coiled belt, a coiled snake and a three-carriage train in front of you. The answer is the small drawing of a suspension bridge behind them all.
2. Try the obvious thing once. It rarely works, and that is the point: the wrong answer shows you which assumption the level is built on.
3. Then attack the frame. Drag objects onto each other, or off the edge of the screen. Drag the question text. Pinch to resize. On a phone, shake it.
4. Buy a hint if you are stuck. The key counter top right starts at 35. Every level has a written hint, and 2 keys skips a level outright.

Five things the game does not tell you:

• The question is an object in 14 levels. Level 22 asks you to put a chicken on every plate and gives you too few chickens — the word "Chicken" in the question is one. Level 219 has you drag the whole sentence down so a monkey can stand on it; level 248 uses it as a gutter.
• The level number is fair game too. Level 78 shows an equation that cannot be true until you notice the level number and drag it into the sum.
• Nine levels hide a piece outside the frame. If something seems to be missing, pinch the whole scene smaller and look at the margins.
• Thirteen levels need real motion — a shake or a flip. That works on a phone and not on a desktop browser, which never reports device motion.
• Repeated questions are traps, not laziness. "How do turtles win rabbits again?" appears at levels 51, 80, 124, 177, 179 and 182, each with a different solution. The wording is identical on purpose, so that you try the last one first.