An internal combustion engine cycle suitable for operation as a two-stroke engine cycle, a four-stroke engine cycle or a higher number stroke engine cycle, when applied to Planetary Gears Reciprocating Pistons Machines with one or more rotating cylinders in order to obtain the reciprocating-piston motion, the cylinder axes thereof arranged substantially tangentially to a circle centred on main shaft axis, whereby the combustion of the working fluid in the cylinder (working fluid being air, fuel or an air/fuel mixture), whether initiated by compression or spark ignition, occurs during the compression stroke of the cycle, thus enabling power to be transmitted on the compression stroke as well as on the expansion stroke.