Playing Bf4 leads to the London System though can quite easily transpose into other lines. Either 2. Bf4 or 2. Nf3 can lead to the London System, which is characterized by development of White's darksquared bishop to avoid blocking it in after play e3.
Closed Game  



Position in ForsythEdwards Notation(FEN)
rnbqkbnr/ppp1pppp/8/3p4/3P1B2/8/PPP1PPPP/RN1QKBNR 
Theory tableEdit
For explanation of theory tables see theory table and for notation see algebraic notation.
1. d4 d5 2. Bf4
2  

Queen's Pawn Game  ... Nf6 
= 
Queen's Pawn Game  ... c5 
= 