the model probably isn't to scale, but if I understand it:
the red things are the cylinders
the silver things inside the red things are connecting rods/pistons
the combustion chambers are in the middle
it is a two stroke, so each piston fires once per rev
the lever in the middle provides offset/variable displacement
when the lever is centered the engine is not firing, but is able to act as a flywheel alone.
the porting is like piston porting in a "normal" two stroke, except it has to happen on that center bearing that connects the cylinders, and through the pivot arm and bearing, somehow.
only the outside part rotates (and the pistons/cylinders), the inside hub is stationary
The main question IMHO is after overcoming the technical challenges remaining, will it weigh less than an optimized engine of the same base fuel consumption with an external energy recovery system, like in F1
Regenerative brake - Wikipedia, the free encyclopedia or a standard issue hybrid. packaging size is also a concern though secondary.