The Two Doors Riddle

You face two doors, each guarded by a figure. One always tells the truth, the other always lies. One door leads to freedom. You get one question.

Easy5 min12,340 plays

The Monty Hall Problem

Three doors: behind one is a prize. You pick a door, the host opens another revealing nothing. Should you switch? A probability puzzle that defies intuition.

Medium10 min9,870 plays

Einstein's Riddle

Five houses, five nationalities, five pets, five drinks, five brands. Only 2% of people can solve this without help. Can you figure out who owns the fish?

Hard30 min5,420 plays

The Bridge and Torch Problem

Four people must cross a bridge at night with one torch. The bridge holds two at a time. They walk at different speeds. What is the fastest crossing time?

Easy8 min7,650 plays

The Pirate's Gold

Five pirates divide 100 gold coins. The most senior proposes a split, and they vote. If rejected, the proposer walks the plank. What should the captain propose?

Medium15 min6,210 plays

The Farmer's Crossing

A farmer must transport a fox, a chicken, and grain across a river. The boat carries only one item besides the farmer. How does he do it safely?

Easy5 min15,890 plays

The Blue-Eyed Islanders

On an island, 100 people have blue eyes and 100 have brown. No one knows their own eye color. A visitor makes an announcement. What happens next?

Hard25 min3,740 plays

The Counterfeit Coin

You have 12 coins and a balance scale. One coin is counterfeit and a different weight. Find it in just three weighings and determine if it is heavier or lighter.

Medium12 min8,530 plays

The Poisoned Wine

A king has 1,000 barrels of wine and 10 prisoners. One barrel is poisoned. Using the prisoners as testers, find the poisoned barrel with one round of testing.

Easy10 min6,780 plays

The Impossible Chessboard

64 coins on a chessboard, a hidden key under one square. Your partner must deduce the key's location after you flip exactly one coin. How do you communicate?

Hard30 min2,150 plays