Nobody Wins
Match a noughts and crosses board that is a draw: every square filled, and neither player with three in a row.
Same encoding as before — rows flattened top-left first, . for empty, 2 hash characters between rows, so the strides are 1, 5, 6 and 4. Two players, one pattern: capture whichever symbol starts a line and let a backreference insist the rest of the line matches it, rather than writing the eight lines out twice. Then say what must NOT be there, and check nothing is still empty.
Wrapped into rows of 3 so you can see the board. The string itself is one line with no line breaks in it — the 2 # between rows are ordinary characters, and a dot will happily match straight past them.
full, but X took the top row
full, but O took the diagonal
nobody has won yet — it is not over
+ 22 hidden tests, checked when you submit. They are what stops a pattern that only fits the examples above.