Chess Opening Theory/1. e4/1...e5/2. Nc3/2...Nf6/3. Bc4/3...Nxe4/4. Qh5/4...Nd6/5. Bb3/5...Be7

Vienna Game, Falkbeer Defence
White can immediately restore material balance with 6. Qxe5 or add another attacker on the e5-pawn with 6. Nf3. After Qxe5 White threatens Qxg7 forcing Black to castle, after which the game can continue in various ways.

If White goes for 6. Nf3 instead, Black will respond with Nc6 and White will take the pawn with Nxe5 threatening Nxf7. Now, Black could castle or trade knights but it is better to kick out White's active queen with 7...g6 forcing White to retreat the queen to e2 or counterattack with Nxc6.

Theory table
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1. e4 e5 2. Nc3 Nf6 3. Bc4 Nxe4 4. Qh5 Nd6 5. Bb3 Be7