<1. e4 c5 2. Nf3 Nc6 3. c3 d5 4. exd5 Qxd5 5. d4 Bf5 6. dxc5 !?> I suppose this is playable and with perfect play might be good for equality, but in seeking an advantage for White I prefer the popular move 6. Be3 to = (+0.45 @ 27 depth, Houdini 5.01 x 64) as in White's win in M Vachier-Lagrave vs D Daulyte, 2017)

<6... Qxd1+ 7. Kxd1 O-O-O+ 8. Ke1> Of the five games in the chessgames.com opening explorer after the forcing moves 6...Qxd1+ 7. Kxd1 0-0-0+ 8. Ke1, Black won four and drew one.

If these practical results are any guide, 6. dxc5!? should perhaps be avoided in serious play -- even though 6. dxc5!? does look like a fun try for skittles and blitz.

<8...Nf6 9. b4> Here the computers recommend 9. Bb5 e5 10. Be3 Nd5 = (0.00 @ 34 depth, Komodo 10) as in Black's win in D Spence vs M Sebag, 2014.

<9... Nd5 10. Bd2 e5 11. Na3?!> This turns the game in Black's favor after 11...a5 (-0.37 @ 33 depth, Stockfish 8.)

Instead, White can hold it level with 11. Be2 = (-0.14 @ 31 depth, Komodo 10.3)

<11... a5 12. Nh4 Be6 13. Nc2 e4 14. g3 Be7 15. Rc1?> This loses because it allows 15...Ne5 (-1.88 @ 27 depth, Komdo 10.3)

Instead, Black can still fight on with hope for a draw after 15. bxa5 Bxc5 (-0.74 @ 28 depth, Stockfish 8)

<15... Ne5 16. Be2 Bh3> (-2.25 @ 31 depth, Stockfish 8) White's position is hopelessly lost.

<17. Ne3 Nxe3 18. Bxe3 g5> This works out fine for Black, but even stronger here is 18... axb4 19. Rb1 g5 (-2.43 @ 30 depth, Stockfish 080417)

1) Removing the guard by capturing the Bishop, in order to avoid 39...Rd3+ 40. Bg3 with a much more difficult winning continuation for Black.

2) Forcing a piece to f3 (decoy tactic) after 39...Rxf2 40. Rxf2 Rd3+ .

Even though Black's advantage would have already been decisive after 15.Rc1? Ne5! in a grandmaster-level game, Black's edge drastically increased after 19.f4? Nd3+! 20.Bxd3 Rxd3 (-4.22 @depth 23).

Instead, White could have put up more resistance with 19.Bd4! Bf6 20.f4 gxf4! (-1.84 @depth 26).

In the game line, Black could have manifested his advantage by playing 24...Rd2!

click for larger view

39. Rxe2 Rxf2 (39. .. Rxf2 (♖f1xf2 ♖e2xf2 ♖d8-d3+ ♘h4-f3 ♗c6xf3 ♔h3-g3 ♗f3-d5+ ♔g3-h4 ♔c8-c7 ♔h4-g5 ♔c7-c6 h2-h4 ♖d3-d4 h4-h5 ♗d5-e6 ♖f2-g2 ♔c6xc5 a2-a3 f7-f6+ ♔g5xf6 ♖d4xg4 ♖g2-e2 ♗e6-d5 ♖e2-e8 ♖g4-g3 ♖e8-c8+ ♔c5-d4 ♖c8-h8 ♗d5-g8 ♔f6-f5 b7-b5) +3.50/23 99)

As you observe, positions such as those after Black's 18th move here -- which look easy to win with GM technique or computer analysis -- are not so easy to win over the board.