Today for game design I have been making placeholder objects for my programming I have been doing this so that when I have finished the 3d modelling I will be able to stick all the code together to make the game working, an example of this is that I have made a default cube which moves and when I add my textured 3d model of it I will put my script onto it.
I have also been using these to use them as experiments as to how the objects will move and interact with each other an example of this is to test if an object can jump, interact with other objects and get affected by things such as gravity.
Games Design Course - Harrison Preston 