I made a word game and I'd like the Scrabble people on this board to tear it apart, because it's built on the one thing you already train: extensions. It's a duel. Two players, one 5x5 grid of letters, the same grid for both of you. You take turns tracing one word on the grid. Every word you play opens a family, and families can change hands. If I play MAIZE and score it, you can play MAIZES on your turn, and the moment you do, MAIZE stops being mine.
The word, the points, all of it moves to your side. So a short word is dangerous to sit on, and going long is how you lock a family down for good. That is hooks and extensions, the same muscle, except against a clock. Scoring is length squared times ten. A 5-letter word is 250, a 7-letter word is 490. The clock is a chess clock. 60 seconds each; a full duel is about two minutes.
The English word list is Collins family, but an old edition: AASVOGEL and OUTWITH are in, SELFIE and EMOJI are not. Minimum word length is 3, so no QI, no ZA. No sign-up, no install, it runs in your phone browser. There's an Elo rating like chess. You can also send a private link to one friend and play only against them. I'm honestly expecting to get beaten here. What's the longest word you managed to steal off someone?
