OOP Project easily expandable

that looks good,
the one change that I might make, simply because I'm a very lazy individual, is to add something like this to the New() method of TEntity:

Type TEntity
	Field x:Int
	Field Y:Int

        Method New()
           if TApplication.MyApp then TApplication.MyApp.AddEntity(Self)
        End Method


	Method Init(x:Int,Y:Int) abstract
	Method Update() abstract
	Method Draw() abstract
	
End Type

you would of course need to have an application created but I can't see why you'd be making entities before then anyway. other than that it looks nice.