Better play Nc3, Nd2, e5 (for advance variation)
French Defence: 3. f3?!

Why do you need games from a database to judge a stupid move?
Black can play pretty much anything (3...de4, 3...c5, 3...Nc6, 3...Nf6) and have a great game right from the start. 3.f3 lacks any inner chess logic.
This surely cannot be worse than the fantasy, and ill judge that by two reasons.
1)his light squared bishop is locked in
2) black will have to waste a tempo on e5 ideas.
Only bright option that may be there is c5 which is probably best, since he can now play it in one move.

Why do you need games from a database to judge a stupid move?
Black can play pretty much anything (3...de4, 3...c5, 3...Nc6, 3...Nf6) and have a great game right from the start. 3.f3 lacks any inner chess logic.
This surely cannot be worse than the fantasy, and ill judge that by two reasons.
1)his light squared bishop is locked in
2) black will have to waste a tempo on e5 ideas.
Only bright option that may be there is c5 which is probably best, since he can now play it in one move.
I'm not an expert like Master pfren, but here are a couple of quick thoughts:
Black's light squared bishop is always a problem in the French Defense (except maybe the exchange), but there are many fine examples of wins with the French.
What are these e5 ideas that black will waste tempo with? Do you mean e6-e5? This just seems to drop a pawn. I'd be very interested in seeing a good example with an early e5 by black.
Black can already play c5 in one move! It's very common in the French Advance variation. Find an example that doesn't by a decent player who knows a little about it and I'll give you something special. I'm not 100% sure, but I think the main line is 1. e4 e6 2. d4 d5 3. e5 c5. Something like Nc6 before moving the pawn seems like a huge mistake. If white immediately captures that c-pawn, black can just play Bxc5, developing their bishop.
It also looks like you're expecting black to transpose into this fantasy, which it does not have to do. I don't know the fantasy opening, but if I chose to play the French Defense, I'd play the French Defense and not transpose.

Your move is not shown in data bases as it is a very bad move which violates chess principals re the French Defense. I suggest you talk to a master or expert to explain to you why it is a bad move.
It would be helpful if you could understand the ideas behind the French Defense.

Your move is not shown in data bases as it is a very bad move which violates chess principals re the French Defense. I suggest you talk to a master or expert to explain to you why it is a bad move.
It would be helpful if you could understand the ideas behind the French Defense.
He posted it on the chess.com forum in hopes of doing so.

Quite often people post new openings on Chess.com because they think the openings are good. And fairly often they try and defend their creation rather than to learn from their mistakes.

It's not so much the 'violation of principles' which is the problem here; rather that there is a simple two-move concrete refutation with the capture and check on h4.
Forget trying to find novelties on move 3. If it's earlier than move 15 and nobody has tried it yet, there's going to be a good reason why not.

EDIT: lol, now i see why, dxe4 fxe4? qh4
My final attempt at coming up with any ideas
^^^ i did already find out why it was bad, simple tactics

Quite often people post new openings on Chess.com because they think the openings are good. And fairly often they try and defend their creation rather than to learn from their mistakes.
True, but they did admit to undestanding why it was wrong.

Hey guys
I know it is an old thread though I am very surprised by the expeditive disregard for this idea.
there is no tactical refutation with 3... dxe4 because of 4.Nc3 and we are now in the Diemer Gambit which must not be overlooked.
3... c5 is certainly good though but not sure Whites have that bad a position. (4.Be3 ? 4.Bb5+ ?)
Probably not the best choice for whites, but is it really not playable?

Lichess likes to humillate himself and share a database containing all of the games played by its users. Here is an illustrative game.

Apart from the tactical problems, Black can always just ignore the pawn and get into positions where the move f3 is just useless or even weakening.

3.Bd3 is the best https://chessmood.com/course/french-defence
People dont read past first post so:
disregard, dxe4 fxe4 qh4+ wins pawn.