Big Bug Bang, the third title in the Captain Blood trilogy (Commander Blood being the second), was - if I recall correctly - only ever released in French (the Wikipedia article on Captain Blood's sequels also seems to support this).
As a huge fan of the first game in the series, I was extremely intrigued to play this game. Not speaking French, however, made this highly impractical (not to mention that the game was probably physically unavailable outside of France - a greater hinderance in the mid-90s than it might be today).
If GOG were ever in a position to re-release this title with a world-first English translation/localization, that would be extraordinary.