Oh, this really is a thing

In between rounds of today's Street Chess event, weird and wonderful opening theory was being discussed. Matt Radisich's favourite Halasz Gambit (1.e4 e5 2.d4 ed 3.f4?) was the kick off point, but it quickly shifted to the Mason Gambit (IIRC). Stephen Mugford was the source of a line that seemed so bizarre that at first I assumed he was just making it up. 1.d4 d5 2.Bf4 c5 3.e4!? were the first few moves and the main line he then showed us continued 3. ... dxe 4.d5 Nf6 5.Nc3 a6 6.Qe2 In response to my incredulity, he mentioned that Luc Winants was a practitioner, at which point I figured it probably was a real line.
It looks like a cross between the London System and a reversed Albin Counter Gambit, but does contain a few drops of poison. The main line (as given above) seems to score well for White, and has been played by a number of strong GM's. But based on the (few) games in my database, developing with 3. ... Nc6 seems to be the best choice, as White scores poorly.
On the other hand, here is an example of what can go wrong for Black if he does take on e4.


McShane,Luke J (2625) - Illescas Cordoba,Miguel (2624) [D00]
EU-chT (Men) 15th Gothenburg (3.1), 01.08.2005

1. d4 d5 2. Bf4 c5 3. e4 dxe4 4. d5 Nf6 5. Nc3 a6 6. Qe2 g6 7. O-O-O Bg7 8. Nxe4 Nxe4 9. Qxe4 O-O 10. Bc4 Bf5 11. Qf3 b5 12. Bf1 Qa5 13. g4 Qxa2 14. gxf5 Qxb2+ 15. Kd2 Nd7 16. Ne2 Nb6 17. Qb3 Qf6 18. Ke1 Qxf5 19. Bh3 Qf6 20. Rg1 Nc4 21. Rg3 Nb2 22. Rb1 Nc4 23. Rd1 Nb2 24. Rb1 Nc4 25. Bg2 Rad8 26. h4 h6 27. h5 g5 28. Bc7 Rd6 29. Bxd6 exd6 30. Qf3 Qd8 31. Qf5 Re8 32. Be4 Kf8 33. Rf3 Qa5+ 34. c3 Ne5 35. Re3 Nc4 36. Rf3 Ne5 37. Rg3 Qa2 38. f4 gxf4 39. Qxf4 Qc4 40. Kf2 Nd7 41. Rxg7 Kxg7 42. Rg1+ 1-0