Projects

Everybody has to get to the other side, and the thing carrying them is too small. Both of these are more about noticing a wrong assumption than about searching harder.

• Four People, One TorchSep 7, 2026A bridge that holds two and a torch that has to come back. Everyone across in seventeen minutes.
• Fox, Chicken, CornSep 7, 2026A raft that holds one thing, and three things that cannot be left alone together.

Games that look like a contest of nerve and are actually already decided. Each one is solved, and the solving is the interesting part.

• Don't Say 21Sep 7, 2026Count to 21 one or two numbers at a time. Whoever says 21 loses — and it is decided long before anyone gets close.
• NimSep 7, 2026Three heaps, take what you like from one. Solved completely, by writing the heaps in binary.

Games where the whole problem is choosing your next question well. Each one is playable in a minute and has a strategy worth arguing about.

• Higher or LowerSep 6, 2026I am thinking of a number. Guess it, then work out how few guesses you needed.
• Pico Fermi BagelSep 6, 2026Guess a number by digit. Each guess tells you how close you are, but never where.

Not part of a set — at least not yet.

• A Hundred LockersSep 7, 2026A hundred kids flip a hundred lockers. Work out which ones end up open, then why.
• Penguins on a PlankSep 7, 2026Twenty penguins turning around whenever they meet. Time how long the plank takes to empty, then scatter them again.
• The Centrifuge ProblemSep 6, 2026Twelve slots, five vials, and the trick that balances them.