Spoiler warning: super-strategy below.
Not a bad idea but since there's no penalty for long strings I can win pretty much instantly by treating it as a typing test and typing a short (probably-unique) substring from each match separated by |. It'll get me an instant-win but if for some reason it matches some non-matches I make it a little longer. Here's a screen grab of me winning with this super-strategy. on this run for some reason you'll notice there's a bug at the end but normally it just lets me win with no chance for the other person to score. I'm not sure how you could address this... If you keep it this way it just becomes a typing test...