How to play
lie.up is a free logic puzzle. Every day there are three new cases, easy, medium and hard, and everyone plays the same ones. In each case, someone took something. The suspects stand in a lineup, each makes one statement, and you work out who is lying and who did it.
The rules
- Exactly one person did it: the culprit.
- Everyone is either honest (every statement is true) or a liar (every statement is false). You aren't told how many liars there are.
- The culprit is always a liar, but not every liar is the culprit.
- The suspects stand in a row, numbered 1 to n from left to right. Your neighbours are the people directly beside you, so the two at the ends have only one neighbour.
- Every case has exactly one answer that fits all the statements, and you can work it out without guessing.
What people say
Each suspect makes one statement. These are the kinds you'll meet:
About honesty: "Ben is lying." "Cleo is telling the truth."
About guilt: "Dan did it." "I didn't do it." "I did it." (That last one is a trap: an honest person can never say it, because the culprit always lies.)
Counting: "Exactly two of us are lying." "At least three of us are lying." "At most one of us is lying."
Pairs: "Ben and I are both honest, or both liars." "Exactly one of Ada and Ben is lying." "At least one of Ada and Ben is lying."
Neighbours: "Both my neighbours are telling the truth." "Exactly one of my neighbours is lying." At the ends of the row: "My neighbour is lying."
Where the culprit stands: "The culprit is one of Cleo's neighbours." "The culprit is my neighbour."
If: "If Uma didn't do it, then Emil is telling the truth."
A worked example
Someone took the last slice of cake. Four suspects stand in the lineup:
1Ada: "Ben and I are both honest, or both liars."
2Ben: "Ada is telling the truth."
3Cleo: "Ben is lying."
4Dan: "I did it."
- Dan. If Dan were honest, he would be the culprit, but the culprit always lies. So Dan is a liar, and his statement is false: he didn't do it.
- Ada. If Ada is honest, Ben is like her, so Ben is honest. If Ada is lying, Ben is not like her, so Ben is honest again. Either way, Ben is honest.
- Ben is honest, so Ada is telling the truth. Cleo says Ben is lying, which is false, so Cleo is a liar.
- Who did it? The culprit is a liar, and the liars are Cleo and Dan. Dan didn't do it, so Cleo did it.
The game starts with this exact case as a short tutorial. Open the handbook on the desk to play it.
Notes and accusing
- Mark each suspect as ✓ honest or ✕ liar while you think. Notes are free.
- When you know who did it, press Accuse…, pick a number and confirm: "Number 4, step forward."
- After each case, How to crack it shows the solution step by step.
Strikes
Each day you have three strikes for all three cases together. Every wrong accusation is a strike. The third one gets you demoted: the case closes unsolved, and the chief wants your badge back until tomorrow. Your streak counts the days in a row without being demoted.
Cold cases and practice
Days you have played go into the cold cases box from the next day on. You can reopen what you didn't crack, with a fresh three strikes. Cold cases don't change your record. The same box has random practice cases at every level.
Questions
- When do new cases arrive?
- At midnight UTC. In Germany that is 1:00 in winter and 2:00 in summer; in New York it is 7 or 8 pm the day before. The desk shows a countdown.
- Do I need an account?
- No. Your progress, notes and record are saved in your browser on this device. Clearing your browser data resets them.
- Can I share my result?
- Yes. After the third case you get a result card with one line per case and your strikes, without any spoilers.
- Is it free?
- Yes.