My favorite approach for finding important files is to look at which files have the most number of changes in the source control. At least with Perforce this is

My favorite approach for finding important files is to look at which files have the most number of changes in the source control. At least with Perforce this is very easy. The files that have many changes are ones where important logic happens. Ones that don't change much are boilerplate, low level object definitions, etc.