Rosentreter Gambit, Testa Variation

The Testa Variation, also called the Testa Gambit, answers 4...g4 with 5. Bxf4. White recovers the gambit pawn but leaves the f3-knight to be captured, much as in the Muzio Gambit. Black almost always takes it with 5...gxf3. White then seeks an attack with the d4–e4 center, the half-open f-file and the active dark-squared bishop. Engines rate Black as clearly better, yet online results are close to even.