Atrachasis
Augur
Learning English with the help of games used to be a piece of cake back in the days of text-based games (ASCII graphics don't count)... I took up gaming in the days of Infocom and Magnetic Scrolls, and even my English teacher nodded his approval at this method.
My suggestion to you would be to consider interactive fiction, as text adventures are called nowadays, rather than RPGs. Graphics-based games just don't contain enough text, nor do they really force you to parse and understand it. An additional advantage is that there are a lot of freeware titles out there, although I have not come across many in French... but do peruse the Interactive Fiction Archive or Baf's Guide (unfortunately, the index of non-English games doesn't appear to be working, but a search for games in French returns 27 titles).
My suggestion to you would be to consider interactive fiction, as text adventures are called nowadays, rather than RPGs. Graphics-based games just don't contain enough text, nor do they really force you to parse and understand it. An additional advantage is that there are a lot of freeware titles out there, although I have not come across many in French... but do peruse the Interactive Fiction Archive or Baf's Guide (unfortunately, the index of non-English games doesn't appear to be working, but a search for games in French returns 27 titles).