Those who venture 1.d4 2.c4 must reckon with the mighty King's Indian Defense. As GM Forintos observed, the K.I.D. typically inspires a "Man Or Mouse" decision, as White usually either wagers his King's safety in order to overrun Black's queenside, or plays like a mouse. The so-called "Hungarian variation" ("Kramer System" sounds weird to me, and "Attack" too promotional) in the King's Indian Defense starts with 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nge2, intending 6.Ng3. It may seem odd to move the KN twice by move six, but the knight supports a potential h4-h5 rush, defends the e4-pawn against knights on f6 and c5, and eyes the critical King's Indian square, f5. Most importantly, the knight's presence on g3 means that a Black pawn won't be arriving there to supervise a Bxh3 sacrifice.
Interested persons may also wish to purchase the favorably-reviewed book on this variation for less than Two Dollars (< $2.00) from Strand.