Static class?

[dleanjeanz]

Can I add 'static' before 'class' instead of adding it before each function to make them all static in this?

class Render {
 	void DrawPlayground();
	void DrawBalls();
public:
	void DrawAll();
};

[Yay295]

Short answer, no.
Long answer, possibly.

[JLBorges]

Use a namespace.

Header file (.h)

namespace Render {
	void DrawAll();
};

Implementation file (.cpp)

// #include header file

namespace Render {

        namespace {

 	      void DrawPlayground() { /* ... */ }
	      void DrawBalls() { /* ... */ }
              
              // variables 
        }

	void DrawAll()
        {
              // ... 
              DrawPlayground() ;
             // ...
             DrawBalls() ;
             // ...
        }
};

[dhayden]

If all methods are static then you should ask yourself why they are in a class. The only thing a class gives in this case is the scoping rules which JLBorges pointed out can be done with a namespace also.