Let me compare Blender Cycles Mode and Blender Game Engine. They both have 5 types of things, being:
Render. Physics. Code. "Objects". Real-Time (speed).
Cycles Mode has SUPERIOR Render, and SUPERIOR "Objects" ex. constraints and a whole bunch a tools. And SUPERIOR Physics accurateness. But lacks in Real-Time speed (unless fast computer?). Last but not least, code, the core of a game, but, does Cycles Mode allow code to make a full game plus allow control so you could interact in the game? (despite speed).
Also explain any limitations Blender Cycles Mode would have.