Lock and Key is a free key and lock puzzle game for kids, played in the browser. Every padlock tells you which key it wants: a clue card such as "Blue", "Not a heart top" or "More than 2 teeth", or a window showing the pins inside, which the right key's teeth must match. Twelve levels go from one lock and three keys to five locks sharing six keys, where opening the easy lock first narrows down the rest. Every board is checked by a solver to have exactly one answer that can be worked out from the clues, so nothing is a guess. Three stars for no wrong keys, a hint whenever you are stuck, and new keys every time you play. No download, no sign-up, works on phones and tablets.
How to play Lock and Key
- Each level has three doors to open. A door is a padlock (or several) and a key board below it with numbered keys. Every key has a coloured top in one of four shapes — round, square, heart or star — and one to four teeth.
- Read the lock. Most locks carry a clue card, and the right key matches every clue on it: "Blue", "Star top", "3 teeth", "Not red", "Fewer than 3 teeth". On the pin levels the lock has a window instead; the right key has teeth exactly the shape of the pins.
- On a level with one lock, tap the key you think opens it. With several locks, tap a key to pick it up and then tap the lock it opens, or drag the key onto the lock.
- A wrong key shakes the lock and is crossed off on that lock, so you never try it there twice. The right key clicks the lock open and stays in it, so it is no longer on the board for the other locks.
- When every lock on a door is open the next door comes up. After three doors the level is done: three stars for no wrong keys, two stars for a few, and one star for any finish.
- Hint shows a lock that only one key can still fit, and which key it is. New Keys deals a fresh set of doors for the same level.
- On a keyboard, number keys pick up (or, with one lock, try) a key, letters A to E try it in a lock, H gives a hint and N deals new keys.
Tips
- With several locks, look for the lock with the fussiest card first. If only one key fits it, open it — that key is then gone, and another lock may be down to one key.
- A "Not" clue rules keys out rather than in. Cover up every key it rules out, and see how many are left.
- Teeth clues use plain counting: "More than 2 teeth" means 3 or 4, and "Fewer than 3 teeth" means 1 or 2. Count the points under the blade, not the top.
- On the pin levels, compare one tooth at a time from the top of the key to its tip. The near-miss keys on level 6 differ in a single tooth.
- On the spare-key levels one key opens nothing, so a key that fits no lock's card is the spare — leave it on the ring.
FAQ
Is Lock and Key free to play?
Yes. It runs in the browser with no download, no account and nothing to buy. All twelve levels are included and unlock one after another as you finish them.
Who is Lock and Key for?
It is made for children who can read short words, from about six or seven, and it is fine for grown-ups too. The first levels need only colours and shapes; later levels add "not", counting teeth and several locks at once, which is real logical reasoning.
How do I know which key opens the lock?
Every clue on a lock's card is true of its key, so the right key is the one that matches all of them. On the pin levels, the right key's teeth have the same shape as the bottom of the pins in the window. Real pin tumbler locks work in a similar way: the key's cuts lift each pin to just the right height.
Do I ever have to guess?
No. Every board is checked by a solver before you see it: it must have exactly one answer, and it must be possible to open every lock by looking for a lock that only one remaining key can fit. If you are stuck, Hint shows you that lock.
How do the stars work?
Three stars means you opened all three doors with no wrong key. Two stars allows a few wrong tries: the limit is the median number of wrong tries of a computer player that reads every card but never plans which lock to open first, over 41 games (and never less than one). Any finish earns one star.
What is the spare key?
On the last two levels there is one more key than there are locks, and the extra key opens nothing. That means you cannot open the last lock just because only one key is left — you still have to check its clues.
Do I get the same puzzles every time?
No. The keys and clues are made fresh for each new game from a seed, and New Keys deals another set at any time. The restart button replays the same three doors.
Does Lock and Key work on a phone or tablet?
Yes. Tap a key, then tap a lock, or drag the key straight onto the lock. The board shrinks to fit a phone held upright, with the buttons underneath.