A dual-crankshaft engine is presented. In one embodiment, the engine includes a first crankshaft and a second crankshaft. The second crankshaft is coupled with the first crankshaft such that the first crankshaft and the second crankshaft are horizontally coplanar. The engine further includes a first piston that is operable to reciprocate in a first horizontal cylinder via coupling with the first crankshaft, and a second piston that is operable to reciprocate in a second horizontal cylinder via coupling with the second crankshaft. The second horizontal cylinder is horizontally collinear with and opposing the first horizontal cylinder.