Semi-Benoni (`blockade variation')
1. d4 c5 2. d5 e5 3. e4 d6
White plays the queen's pawn to d4. Black plays the c-pawn to c5. White pushes the queen's pawn to d5.
Black pushes the king's pawn to e5. White plays the king's pawn to e4. Black pushes the queen's pawn to d6.