Here’s a Rotary Radial engine:
Apparently, these were developed (back in WW1 
) because their rotation helped to aspirate the engine, as well as to further cool it. To me, it would also seem that this engine rotation could perhaps also usefully counter torque.
Obviously this particular model is large, as it’s meant for a full-sized aircraft.
Has any smaller version of something like this ever been used with a paramotor?