The twenty five horses
Level 4 · Advanced · ●●●●○
You have 25 horses and a race track with 5 lanes. You need to find the 3 fastest horses. You don't have a stopwatch, you can only know the relative order of...
Master plays
Strategy and game-theory puzzles where planning multiple moves ahead matters.
The five pirates
Level 4 · Advanced · ●●●●○
Five perfectly rational and selfish pirates (A, B, C, D, E, in order of rank) find 100 gold coins. They must decide how to distribute them according to this...
The three blind wise men
Level 5 · Expert · ●●●●●
Three perfectly logical wise men are sitting in a circle. The king shows them 5 hats: 3 white and 2 black. He blindfolds them, puts a white hat on each one,...
Nim (3,4,5) in misère mode
Level 4 · Advanced · ●●●●○
There are three piles with 3, 4 and 5 chips. On each turn you can remove any positive number of tokens, but from a single pile. Misère rule: Whoever takes th...
The desert expedition
Level 4 · Advanced · ●●●●○
Crossing the entire desert requires exactly 6 days. Each explorer can carry supplies for a maximum of 4 days. Explorers can: walk together, transfer food, an...
The relay of messages
Level 4 · Advanced · ●●●●○
Four spies A, B, C and D each have a different secret. In each phone call, the two participants tell each other everything they know up to that moment. Quest...
The impossible coloring from 1 to 5
Level 4 · Advanced · ●●●●○
You want to color the numbers \{1,2,3,4,5\} with two colors (red and blue). The prohibited rule is: there cannot be three numbers of the same color x,y,z tha...
The scale and the different ball
Level 3 · Intermediate · ●●●○○
You have a scale with two plates and three visually identical balls. You know that one ball weighs differently than the other two, but you don't know if it i...