Four knights - Schultze-Mueller gambit
1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5
White moves the king's pawn to e4. Black moves the king's pawn to e5. White develops the knight to f3.
Black develops the knight to c6. White moves the knight to c3. Black transfers the knight to f6.
White captures with the knight on e5.