NEW-REVITALIZED French Defense!
Nowadays I use the NEW-REVITALIZED French Defense! Indeed my very first success against a truly tough player (a draw in a club tournament game with a 2300 rated player back in the early-80's) happened in this virtually unknown line.
Before talking about the French, here's some relevant background . . . from a guy who absolutely does NOT believe in memorizing opening lines ....
Back, almost 40 years ago, when I was a high school Spanish teacher in the United States I totally ran two scholastic chess clubs and occasionally assisted other chess clubs at the primary, elementary, middle-school, junior high and high school levels and was involved in a combined five state scholastic chess championship teams and a couple seconds and a 3rd at various levels in four years. My 'curriculum' was always the same: a) Emanuel Lasker's 7 Goals for the first 12 moves b) sample miniature games in perhaps 20-25 openings c) endgame principles and endgame puzzles d) typical mating patterns d) 17 key tactical motifs e) key strategic ideas arising out of opening pawn structures and f) using every opening a player desired, but in tournament play employing the Blackmar-Diemer Gambit as White and the French D as Black with 1. ... e6 used against d4. I never taught moves or move order and it worked real well.
I still play the BDG an awful lot even though it's no longer considered exciting or intriguing, but rather today seen as UNSOUND. But when I play e4 and run into the Center Counter (Scandanavian 1. ... d5) I'll convert back into the BDG with 2. d4. Why? Because I found strictly playing in the main lines of the Scandanavian were tougher (for me) than their reputations would indicate. But I also found out that IF I, on the other hand answered 1. e4 with d5; about 1/5 or 1/4 of the time I wound up playing the NEW-REVITALIZED French Defense after quite a lot of White players responded with 2. e5!? and my 2. Bf5 seemed a natural and strong move which so far 99% has ended up in a totally new French D. I can't believe that the 2. e5 response (hoping for the regular French, I suppose) can be considered a worthy move, but against club players I wind up in my N-R French about four games out of any nine. In any case, the main point of this little note is my notion that until an absolute irrefutable-bust for 2. e5 vs the Scandanavian is found, you, as the Black player, can often find yourself in dynamic and unique board situations by getting into the N-R French via the Scandanavian. It's not quite as gnarly-ugly as playing the French against a real strong player, but there are no BOOK LINES out there.
IF, of course, White 2. exd5 . . . play often leads into Mieses' version of the Scandanavian with 2. ... Qxd5 3. Nc6 Qa5. There are several other credible, but infrequently-played lines available (Black has had some success with 3. Qd6 or avoiding the recapture with 2. Nf6, or 2. e6 or even 2. e5. But, be warned, totally unique pawn structures and tactics await! In any case roughly 95% of my games wind up in the N-R French 23% or the Mieses Variation after QxP. Good luck.
RPV
Nah! Speaking as a French player for 20 years and still playing the French 95 percent of the time against 1.e4 (I occasionally play 1...e5 and if 2.Nf3, the Petroff).
Best line against the KIA is 1.e4 e6 2.d3 d5 3.Nd2 Nf6 4.Ngf3 c5 5.g3 Nc6 6.Bg2 Be7 7.O-O O-O 8.Re1 b5 9.e5 Nd7 10.Nf1 a5 11.h4 Ba6 12.N1h2 b4 and now if 13.Bf4 then 13...a4 while if 13.Ng4, then 13...Nd4 (13...a4 is still an option). In the latter, White is forced to take on d4, giving you an open attack on the backwards c-pawn because if he does not capture, then 14...Nf5 stops up the attack by White completely.
Over on www.charlottechesscenter.org, I write for the blog, and from March to now, I have written 16 articles on the French, called "The French Connection" if you want some sample material for pattern recognition and ideas. Many different variations occur in those 16 articles, including the Winawer, Steinitz, McCutchen, Tarrasch, King's Indian Attack, Advance, Exchange, and even one on how to counter garbage lines (Volume 9).