An internal combustion engine is provided. The engine includes a housing (9) having at least first and second pairs of chambers (20) formed in the housing. Each chamber extends from the exterior of the housing to a predetermined point therein. The first pair of chambers being aligned with the housing along a first axis and the second pair of chambers being aligned within the housing along a second axis extending substantially normal to the first axis. The engine further including a plurality of piston assemblies (6). Each chamber having one of the piston assemblies rigidly fastened thereto. A cylinder (1) is reciprocally mounted on an elongate cylinder pin assembly (2). The cylinder pin assembly extending within the housing and disposed between the cylinders for reciprocating the cylinders along a predetermined stroke length and relative to the fixed piston assemblies in an opposed manner during operation of the engine. The cylinder pin assembly having two axes of rotation. The engine also including a power takeoff shaft (12) coupled to an end of the cylinder pin assembly for transmitting energy generated by operation of the engine.