> That is, any sufficiently mature indie game project will end up implementing an informally specified, ad hoc, bug-ridden implementation of Unity (... or just use the informally specified, ad hoc and bug-ridden game engine called "Unity")

For the 4 people on HN not aware of it, this is a riff on Greenspun's tenth rule:

> Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.