It is a class publishes a set of properties from its ancestor, TCustomMesh, in order to let you design new 3D shapes at design time from within the IDE, through the Object Inspector. TMesh is a custom 3D shape that can be customized by drawing 3D shapes. To create a 3D object to be used in Viewport3D we need to use TMesh classes.

You can also easily load your 3D objects into Viewport3D by using Model3D ( TModel3D). Please see this post about Working With 3D In Modern Windows C++ Development for creating these 3D objects.

Viewport3D ( TViewportd3D) component in C++ Builder FireMonkey projects is good to display many basic 3D Objects like Plane, Cube, Sphere, Cone, Plane, Ellipse3D etc.

In C++ Builder you can directly create your own 3D objects, you can animate them on runtime. You can use OpenGL or Direct3D libraries or some other 3rd party 3D Engines. C++ is faster programming language that you can develop fully native and faster games. C++ Builder is easy to build these kind of simple games.

How to create your own game with c++