Abstract: A multi-chamber rotary piston internal combustion engine includes an engine housing having interior walls defining a plurality of internal cylindrical cavities, at least one of the cavities being disposed in a first housing level and at least one other of the cavities being disposed in a second housing level spaced apart but adjacent to the first housing level. A plurality of rotary pistons and cylinders are movably mounted relative to the cavities which, in operation, cooperatively define, at least partially with the housing interior walls, a multiplicity of sequentially-arranged chambers including a gas intake chamber, and at least one gas compression chamber located in the first housing level and an ignition chamber, gas expansion chamber and a gas expulsion chamber located in the second housing level, with the cylinders, pistons and cavities being operatively arranged so that gas intake, compression, ignition, expansion and gas expulsion take place simultaneously during one revolution.