Digital Advent Calendar: 24 Puzzle Ideas With Locks

A digital advent calendar with locks is a countdown where each day's window is a small puzzle: solve it, enter the code on your phone, and the day's surprise appears (a message, a challenge, a voucher, a photo, a video). You make one lock per day on CrackAndReveal, share its link or QR code on the right morning, and give a clue to the code. Below you will find all 24 days written out for a family, with the riddle, the lock type, the exact code and what each lock reveals.

One practical point first: a multi-lock chain holds 2 to 10 locks in a row, so it cannot hold 24 days. The calendar is 24 separate locks, one link per day. (A chain is perfect for the Christmas Eve finale, and day 24 below uses one.) The budget section explains honestly when the 30-day Event Pass is worth 9 euros.

How a digital advent calendar with locks works

Each day has three parts:

1. The clue. Something the player must read, find or work out: a riddle, a sum, a hiding place, a tune to hum.
2. The lock. The code goes into a virtual lock: digits, a word, colors, arrows, a drawn pattern, piano notes, switches or a spot on a map.
3. The reveal. The content that appears when the lock opens: text, an image, a sound, a video or a link.

You choose how the daily link reaches the player. Three simple options:

• Printed QR codes in numbered envelopes, jars, paper bags or toilet-roll tubes hung on a string. This is the DIY advent calendar version: a physical calendar where every window holds a QR code and a clue instead of a chocolate.
• One message a day (text, family group chat, email) that you schedule in advance with your messaging app.
• A single page that lists the days, with only the current day's link added each morning.

A link on its own opens nothing; the player still needs the code. So even if a child scans tomorrow's QR code early, they still have to solve tomorrow's clue.

The 24 days: a complete calendar for a family

This calendar is written for a family with children around 6 to 12, and it runs from December 1 to December 24. Every riddle and code below has been checked. Swap names, places and rewards for your own.

A few conventions: numeric codes are four digits, passwords are not case sensitive, and the Free plan includes all 14 lock types, so you can reproduce every day without paying.

Week 1: December 1 to 7

| Day | Clue given to the player | Lock | Code | What it reveals | |-----|--------------------------|------|------|-----------------| | 1 | "The calendar ends on the 24th of the 12th month. Write it as day then month." | Numeric | 2412 | A welcome letter explaining the rules, plus a first small treat | | 2 | "I fall but never get hurt. I am white, cold, and I cover the rooftops." | Password | snow | Challenge: build a snowman, real or drawn, and send a photo | | 3 | "Look at the Christmas lights on the tree, from top to bottom." | Color | red, green, yellow, blue | Voucher: you choose tonight's film | | 4 | "The reindeer walks to the barn: two steps up, one step right, one step down." | Directional 4-way | Up, Up, Right, Down | Voucher: hot chocolate with marshmallows | | 5 | "Santa has 8 reindeer, plus Rudolph. Each one eats 12 carrots a day. How many carrots in all?" | Numeric | 0108 | A drawing challenge: draw the ninth reindeer | | 6 | "Draw the first letter of the word LIGHTS: go down the left column, then along the bottom." | Pattern | 0, 3, 6, 7, 8 | A tiny gift tucked in a shoe (St. Nicholas Day in many countries) | | 7 | "Light up the tree on the grid, as drawn on your sheet." | Switches 4x4 | 0110011011110110 | "Today we decorate the tree together" |

How the Week 1 codes work:

• Day 1: 24 and 12 give 2412. The order (day, then month) is in the clue.
• Day 3: the colors are the order of the lights you hang on the tree yourself. Hang them in that order, top to bottom, the evening before.
• Day 5: 8 reindeer plus Rudolph is 9. 9 times 12 is 108, entered as 0108.
• Day 6: the grid points are numbered 0 to 8, row by row, from the top left. 0, 3, 6 goes down the left column and 7, 8 goes along the bottom, which draws an L.
• Day 7: the switches grid below is read row by row, 1 meaning "on".

0 1 1 0
0 1 1 0
1 1 1 1
0 1 1 0

Printed on the clue sheet as an empty 4 by 4 grid with a small tree drawn beside it, the child fills in the squares that make the tree. Reading it row by row gives 0110011011110110.

Week 2: December 8 to 14

| Day | Clue given to the player | Lock | Code | What it reveals | |-----|--------------------------|------|------|-----------------| | 8 | "Every letter has moved 3 steps forward in the alphabet. Decode VWDU." | Password | star | Challenge: cut star-shaped biscuits or paper stars | | 9 | "Hum it: Jin-gle all the way." (a parent plays the tune) | Musical | E4, G4, C4, D4, E4 | A family sing-along, with a link to lyrics | | 10 | "Find the four sticky notes hidden in the house, each with one digit." | Numeric | 7319 | A funny voice message from a grandparent | | 11 | "Santa's workshop login. Username: the smallest helper. Password: what elves drink to stay warm." | Login | elf : cocoa | A letter "from the elves" with a small mission | | 12 | "Follow Santa's compass on the map: north, north-east, east, south, south-west." | Directional 8-way | N, NE, E, S, SW | Big prize, halfway: a movie night with popcorn | | 13 | "Light the four corners of the tree, clockwise from the top left." | Ordered switches 4x4 | 0, 3, 15, 12 | A baking session: gingerbread or cookies | | 14 | "I have a face and two hands, but no arms or legs. What am I?" | Password | clock | Late-bedtime voucher: 15 extra minutes tonight |

How the Week 2 codes work:

• Day 8: this is a Caesar cipher with a shift of 3. To decode VWDU, move each letter back 3: V becomes S, W becomes T, D becomes A, U becomes R. The answer is STAR. Give younger children the alphabet written out and a strip of paper to slide.
• Day 9: the tune is the end of the chorus of Jingle Bells (a public-domain carol). In the key of C, the five notes are E, G, C, D, E, all inside the single octave C4 to B4 that the musical lock offers. If nobody in the family can play, search for a keyboard demo online and let the child pick out the notes.
• Day 10: place the four sticky notes with 7, 3, 1 and 9 in four rooms and number the notes by a clue ("kitchen first"). The code is 7319.
• Day 11: elf is the username, cocoa is the password. The lock is written as one pair, username then password.
• Day 12: the compass directions N, NE, E, S, SW are 5 steps, well inside the 8-step maximum. Draw a compass on the clue and let the child trace the route on a map of "the North Pole".
• Day 13: a 4 by 4 grid is numbered 0 to 15, row by row. The corners are 0 (top left), 3 (top right), 15 (bottom right) and 12 (bottom left), clockwise from the top left. The order matters on an ordered-switches lock.
• Day 14: the answer is a clock.

Week 3: December 15 to 21

| Day | Clue given to the player | Lock | Code | What it reveals | |-----|--------------------------|------|------|-----------------| | 15 | "Santa's official hometown is in Finnish Lapland. Find the city on the map." | Virtual geolocation | Rovaniemi, Finland (tolerance 25 km) | A short video message "from Santa" and a bedtime story | | 16 | "Light the Advent wreath: the first, second and fourth candles are the same color, the third is a different one." | Color | purple, purple, pink, purple | Light the real candles tonight and share a story | | 17 | "There are 8 days until Christmas Day. Multiply that by the 9 reindeer." | Numeric | 0072 | A mission: write a card for a grandparent | | 18 | "Draw the first letter of Noel: up the left, down the diagonal, up the right." | Pattern | 6, 3, 0, 4, 8, 5, 2 | Kindness challenge: pick a toy to donate | | 19 | "Read it backwards: y-l-l-o-h." | Password | holly | Craft: make a wreath with leaves and ribbon | | 20 | "Twinkle, twinkle, little star: play the first line, all seven notes." | Musical | C4, C4, G4, G4, A4, A4, G4 | Family film night with a blanket fort | | 21 | "The longest night of the year: light the snowflake on the grid." | Switches 4x4 | 0110111111110110 | Winter solstice evening: candles, blankets, stories |

How the Week 3 codes work:

• Day 15: the lock is a virtual map. The player drops a pin near Rovaniemi, the city in Finnish Lapland that presents itself as Santa's hometown; with a tolerance of 25 km, a finger tap in the right area is enough. The starting view of the map is never centred on the answer, so the children really have to look for the town.
• Day 16: the traditional Advent wreath has three purple candles and one pink one, with the pink candle lit on the third Sunday. Many modern wreaths use other colors, so print the colors on the clue to avoid ambiguity.
• Day 17: from December 17 to December 25 there are 8 days. 8 times 9 equals 72, entered as 0072.
• Day 18: the pattern is an N: up the left side (6, 3, 0), diagonally down to the bottom right (4, 8), then up the right side (5, 2).
• Day 19: reading y-l-l-o-h backwards gives h-o-l-l-y.
• Day 20: Twinkle Twinkle Little Star is also public domain. C, C, G, G, A, A, G is seven notes, inside the C4 to B4 octave.
• Day 21: the snowflake grid is the same trick as the tree on day 7.

0 1 1 0
1 1 1 1
1 1 1 1
0 1 1 0

Read row by row, it gives 0110111111110110.

Week 4: December 22 to 24

| Day | Clue given to the player | Lock | Code | What it reveals | |-----|--------------------------|------|------|-----------------| | 22 | "Go to the place where we take the family photo every year." | Real GPS geolocation | Your local spot (tolerance 50 m) | A photo challenge and a hot chocolate on the spot | | 23 | "I hang above doorways, and people stop underneath me for a kiss." | Password | mistletoe | A dance party in the kitchen | | 24 | Christmas Eve test in three steps (a chain) | Multi-lock chain, 3 locks | See below | The main gift |

• Day 22: this lock only opens when the phone is physically near the target place. It is designed for good-faith play (a determined player could fake a GPS position), which is perfectly fine for a family walk. Choose a spot that gets a decent signal.
• Day 23: the answer is mistletoe. Add a hint card showing the first and last letters if your child is younger.

Day 24, the finale, is a chain of three locks in a row:

1. Numeric, code 0024: "How many windows have you opened since December 1?"
2. Password, code family: "The word you find on every photo frame in the hall" (stick a card saying FAMILY on the tree).
3. Musical, code G4, A4, G4, E4: the first four notes of Silent Night, the carol everyone knows (public domain).

The last lock reveals the big surprise: a letter, a video from the whole family, a plan for Christmas day, or the clue to where the main gift is hidden. Because a chain has between 2 and 10 locks, you could also build one chain for each of the four Advent Sundays.

Make it your own: versions for every group

The 24-day structure stays the same. What changes is the tone, the type of puzzle and the reward.

Advent calendar ideas for kids

• Ages 4 to 6: use only colors and short numeric codes. A parent reads the clue aloud and the child taps the colors. Keep the reveals physical (a sticker, a hug, a song).
• Ages 7 to 10: add password riddles, simple sums and directional locks.
• Ages 11 and up: introduce the Caesar cipher, the ordered-switches lock and chains.
• Always pair a puzzle day with an easy day. A calendar that is hard all month turns into a chore.

Advent calendar ideas for adults

Adults like a bit of wit and a reward that is more than a chocolate. Swap the Santa riddles for lateral thinking, quizzes and shared memories:

| Day | Idea | Lock | What it reveals | |-----|------|------|-----------------| | 1 | The date you met, as MMDD | Numeric | A memory and a photo | | 4 | The street of your first apartment | Password | A voucher for a dinner out | | 8 | The route of a walk you took together, as arrows | Directional 8-way | A playlist of the songs of the year | | 12 | A sequence of three colors tied to a trip | Color | A weekend plan or a handwritten letter | | 16 | The city where you first travelled together | Virtual geolocation | A voucher for a small trip | | 20 | The first notes of your song | Musical | A voice message | | 24 | A chain of three: date, place, word | Chain | The main gift |

This is also a good place to link the calendar to your musical lock Advent puzzle if you want a calendar built around tunes. For a couple, the entire calendar can be a story told over 24 days: each reveal is the next chapter of how you met.

Advent calendar for colleagues and teams

Send a link every working day and keep the tone light. A team calendar can combine fun with useful content: a tip of the day, a quiz, a message from management, a vote for the best festive jumper. Skip weekends (December 2026 has 18 working days from December 1 to 24) and finish with one team-wide puzzle. Here is more on that format: Christmas animation for the works council and a digital advent calendar for your brand. Competition mode, which ranks the first teams to open the lock, is part of the Pro plan.

Advent calendar puzzles for a class

Teachers can run a 10 to 15 lock calendar over the school days before the holidays, with a review question hidden in each puzzle: a spelling word, a times table, a capital city on the map lock. The code is the answer; the reveal is a Christmas fact, a joke or a drawing task. A class of children can solve in teams on a shared screen, which keeps the number of attempts down.

Planning: how long it takes and when to start

The calendar is much quicker to prepare than it looks, especially if you reuse the 24 days above. A realistic plan:

| When | Task | Time | |------|------|------| | Early November | Choose the audience and the 24 rewards; list the reveals first | 1 hour | | Mid November | Write the 24 clues and check each code | 1 hour | | Late November | Create the locks (a lock takes a few minutes once your text is ready) | 2 to 3 hours | | Last weekend of November | Test one or two locks yourself, then print QR codes or schedule messages | 1 hour | | December 1 | Open day 1 and keep the next days ready | 5 minutes a day |

You can also let an AI assistant create the locks for you: ChatGPT and Claude can build a lock from a description through the MCP page. Paste your table of days and ask for one lock per day, and check the codes before sharing.

For the step-by-step creation walk-through (screens, settings, QR codes), see our dedicated guide: how to create a digital advent calendar escape game step by step. This page is the idea list; that one is the tutorial.

Budget: attempts, the Free plan and the Event Pass

Here is the honest maths, because it decides whether you pay anything.

• Free gives you unlimited locks, all 14 lock types and 30 player attempts in total, counted across all your locks. Your own tests count too. Every try at a code, right or wrong, is one attempt.
• A calendar with 26 locks (23 single locks plus a 3-lock chain on day 24) needs at least 26 attempts if every player gets each code right on the first try. In practice children try more than once, so Free will not cover a whole month for a family.
• Test sparingly. Open one or two locks yourself, not all of them.
• Event Pass: 9 euros (9 dollars outside the euro zone), one-time, taxes included, with unlimited player attempts for 30 days. Nothing renews. If you buy it at the start of December, it covers the whole calendar, Christmas Day and the first days of January.
• You do not have to buy on December 1. Start on Free, and if the 30 attempts run out mid-month, buy the Pass then. It still covers the rest of December. Thirty days is from the day you buy it.
• The Pass does not include the Pro features (competition mode, no watermark, iframe embedding). Pro is 29 euros, one time, for life. A company calendar that wants a leaderboard or no watermark needs Pro.
• Every purchase has a 14-day money-back guarantee.

Common mistakes to avoid

• Making codes too hard. If a child fails a code for two days in a row, they stop playing. Offer a hint card in an envelope.
• Forgetting that sums need a four-digit code. Write 0072, not 72.
• Letting the clue and the code drift apart. Re-read every clue the night before and run the sum once more.
• Sending all the links on December 1. Send only today's link. The surprise and the daily habit are the point.
• Building a gift that needs everyone in the same place. If the family is split across countries, send a link and a voice message instead of a physical reward.

More Christmas puzzle ideas: a Christmas family escape game with padlocks and Christmas and New Year puzzles with switches.

FAQ

What is a digital advent calendar?

It is an advent calendar where each of the 24 days is a link or QR code instead of a cardboard window. Behind each link is a puzzle that has to be solved before the surprise appears. You can make it for children, a partner, friends, colleagues or students.

How many locks do I need for a digital advent calendar?

One per day, so 24, or a few more if you use a chain for a finale. A multi-lock chain holds 2 to 10 locks in a row, so it cannot replace the whole calendar. Use separate locks for the 24 days and a chain for Christmas Eve if you want a longer final challenge.

Can I make a DIY advent calendar with QR codes?

Yes. Create each lock, download its QR code, print it and put it in a numbered envelope, jar or paper bag with the day's clue. The QR code opens the lock, and the player must solve the clue to open it.

Is it free?

You can create unlimited locks on the Free plan. Free includes 30 player attempts in total across all your locks (your own tests count). For a full calendar played every day, plan on the Event Pass: 9 euros (9 dollars elsewhere), one-time, 30 days of unlimited attempts, no renewal.

How do I stop children opening several days at once?

Give them only today's link or card. Even if they scan tomorrow's QR code, they still need tomorrow's clue to find the code. Keep the clues in a sealed envelope or send them on the day.

Which lock types work best for young children?

Color locks and short numeric codes. A parent reads the clue, the child taps the colors or digits. From age 7 or 8, add short password riddles and arrows.

What can I hide behind the lock?

Text, an image, a sound, a video or a link: a voucher, a family photo, a voice message, a task, a playlist, or a clue to a physical gift.

Can I create the locks from ChatGPT or Claude?

Yes. Both can create a lock from a description through the MCP server (see the page at crackandreveal.com/mcp). Check each code before you share a link.

Conclusion

A digital advent calendar with locks turns 24 identical windows into 24 small moments of play: a riddle at breakfast, a code in the evening, a surprise that was worth the wait. Reuse the 24 days above for a family, or adapt the table for adults, a couple, colleagues or a class. Start preparing now: with the whole of November to create the locks, testing once and opening the calendar on December 1, you only need to pay if your players go past the Free attempts.