Abstract: An internal combustion rotary engine with multiple cylinders and rotary crankcase supported on a pair of engine stub shafts. The connecting rods are each connected to a different center arranged evenly around the drive center of a stepdrive element. The stepdrive element which is polygonal or circular is offset from the rotational axis of the crankcase within which it revolves. The stepdrive element drives the crankcase through a series of links. As each piston fires the connecting rod is inclined to the piston travel axis and the angle between the connecting rod and the stepdrive element center is close to 90 degrees. As the piston moves through its power stroke the cylinder rotates with the crankcase maintaining the mechanically advantageous 90 degree angle for about 100 degrees of crankcase rotation. Symmetric and asymmetric cylinder layouts, Diesel and 2-stroke layouts are disclosed.