The paper proposes a modified gravity theory where an arbitrary function of the Gauss-Bonnet (GB) term is added to the Einstein action to serve as a gravitational alternative for dark energy. This modified theory is shown to pass solar system tests and can describe key features of late-time cosmology, such as the transition from deceleration to acceleration, crossing the phantom divide, and current acceleration with an effective equation of state (cosmological constant, quintessence, or phantom). The authors demonstrate that for a reasonable choice of the function \( f(G) \), the theory can explain these cosmological phenomena. They also provide explicit examples of the function \( f(G) \) and show that the theory can lead to rich and realistic cosmological dynamics, including transitions between different phases of the universe.The paper proposes a modified gravity theory where an arbitrary function of the Gauss-Bonnet (GB) term is added to the Einstein action to serve as a gravitational alternative for dark energy. This modified theory is shown to pass solar system tests and can describe key features of late-time cosmology, such as the transition from deceleration to acceleration, crossing the phantom divide, and current acceleration with an effective equation of state (cosmological constant, quintessence, or phantom). The authors demonstrate that for a reasonable choice of the function \( f(G) \), the theory can explain these cosmological phenomena. They also provide explicit examples of the function \( f(G) \) and show that the theory can lead to rich and realistic cosmological dynamics, including transitions between different phases of the universe.