Choose who drinks from each bottle. Then poison one at random — can the list of who died tell you which bottle it was?
One marble is secretly heavier than the rest. Use the balance scale to find it in as few weighings as you can.
Ferry the fox, the goose, and the beans across the river. The boat holds you plus one passenger — and whatever you leave behind must not become a meal.
Four people must cross a rickety bridge at night with one flashlight. At most two cross at a time, a pair moves at the slower one's pace, and the flashlight has to come back for the others. Get everyone across in as little time as you can.
Each dwarf holds a sack. One bulges with gems 💎 — the other two are full of dung 💩. Pick a sack; a dwarf opens a losing one; then decide — keep yours, or switch?
No measuring marks — just two jugs and a tap. Fill, empty, and pour between them until one jug holds exactly the target.
Take as many stones as you like from a single row — but only one row per turn. Whoever grabs the very last stone wins. The computer plays perfectly; can you find the trick to beat it?
Move the whole stack to the right-hand peg. One disk at a time, and never a larger disk on a smaller one. Click a peg to lift its top disk, then click where to drop it.
Tap a tile and it flips — along with its four neighbors. Turn the whole board dark. Sounds easy; the neighbours are what make it a puzzle.