Word Games
Ghost Trap
The schoolyard word duel. Take turns adding ONE letter to a growing fragment — keep it the start of a real word, but whoever finishes a word LOSES. Spell people into a corner. Solo bot ladder + live class arena. Hiding underneath: every fragment is a solved win-or-loss position — the exact theory that cracks Nim, now on the dictionary.
For Educators
Built for the classroom
Spelling, vocabulary, and prefix awareness — every move is a question of "what real words start like this?" — wrapped around real combinatorial game theory. Students discover that some fragments are TRAPS: positions where every letter you can add loses, no matter how clever you are. That win/loss value of every fragment is decided by backward induction over the dictionary's prefix tree — the same P-position / N-position (Sprague–Grundy) theory that powers Nim Arena and Chomp Arena, only the board is the English lexicon. The boss bot, The Lexicon, plays that solved value perfectly; beating it (the Dojo's Trap Finder colours every letter win/safe/lose) earns the License and unseals the theorem. Clean common-word list (no obscure or rude words); the strategy famously depends on which dictionary you use.
Grades 4+ · one shared list of ~2,500 common 4+ letter words · solo bot ladder (Rookie → Hungry → Trapper → The Lexicon); the empty fragment is a first-mover win, so the arena swaps who goes first each round.
Three ways to play
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Learn solo first
Four bots, all open: Rookie, Hungry, Trapper, The Lexicon. Each sees one move further. The 📓 Trap Finder colours every letter — green wins, yellow is risky, red finishes a word — so you learn to see the traps.
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Host an Arena
Open a room on the projector; a 4-letter code + QR + join link appear. Students are paired and play best-of-2 (each goes first once — the first letter is an edge). Watch the live ladder climb.
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Join on any device
Add a letter from the keyboard (only legal letters light up). Finish a word and you lose the round. Matches rotate so everyone plays everyone — no waiting, no elimination.
Run a live class in 5 steps
- Open the Arena — set the session length and the move timer; share the 4-letter code / QR / link.
- Students join on any device and are paired into best-of-2 duels (the first letter swaps each round).
- Each turn: add ONE letter, keeping the fragment the start of a real word. Finish a word and you lose the round.
- Ask the room mid-game: which fragments felt doomed no matter what you added? Those are the traps.
- Send the fast finishers to the Dojo's Trap Finder — and ask why the perfect bot never lets go of a win.
Tip: host on a laptop or projector (the big screen shows the code, QR and leaderboard); students join on their phones or laptops.
