Honestly ... did you really done it with C3, or was it pure ThreeJS controlls ? Can´t believe it. One thing i noticed: it seems you use "WebAssembly", which is nice. But i would build in a drawback to ASM.js or something similar. Because i can´t play it on older machines / browsers. Especially don´t use WebGL 2.0 , because it is not wide spreaded and performance in comparison to 1.0 isn´t so nice. If you done it in combo with C3, it seems like good progress !
The control is completely over construct 3 (8 Dir movement). But, i think the better engine is babylon.js .
(Better documented etc)
The fastest way is, to place the babylon (or three.js) canvas behind the construct canvas. It't not a good idea (performance), to copy the babylon canvas to the construct canvas.