Pack 6 Tricky patterns

Tricky patterns is an advanced pack built on backreferences and lookahead. A backreference like \1 matches the same text a group caught earlier, and a lookahead like (?=…) checks what comes next without using it up. Together they handle rules that classes and counts can’t express.

The first board catches words where one letter appears three times, like banana and assess. Then come words that start and end with the same two letters, like onion, strings where no character appears twice in a row, numbers whose digits only go up, like 2489, one level of parentheses, and a word said twice in a row, like couscous. Each trap is there to break the lazy answer.

Every level also has hidden checks: words you don’t see. Passing the words on screen solves a level; passing the hidden checks too ranks it.

If you enjoy these, Regex wizardry is harder still. The Groups & backreferences track explains capture groups from the start.