Midterm - Game and Game Controller

My game is a multiple player game. So far for the Midterm, I made only one player just to make sure the logic flow is correct. It's a story about some robots are trapped in mountains , and they should  dig the mouton and find as much candy as they can.

Basically, robot spins all the time. Player can control it stop spinning and start to walk. Also, Player can control the robot shot mountains or other robot.

I made all materials in Cinema 4D , I like low-poly style so much, so I try this style in my game.

For the controller, I want to use two BIG buttons because I like the press feelings. However, too big buttons means big controllers, so I consider to make a suitable shape to help people easily hold it and control it.