Main moves: 1. d4 d5 2. c4 e5 3. dxe5 d4. Black hits back immediately for space and activity.
Typical themes: the d3 wedge, rapid development, and dynamic counterplay. References: ECO D08—D09, Wikipedia, Chess.com, 365Chess.
Opening moves: 1.d4 d5 2.c4 e5 3.dxe5 d4
Update the move sequence above to match this opening.