IANAL but copyright is typically the year of first publication.

I could see this being important here in two ways:

1. If the source code of Zork has not been made available to the public before, then now is the year of publication.

2. If Zork source code has previously been made available to the public, perhaps the version published here has had changes made, in which case now is the year of publication of this version of the source code.

I assume that when Microsoft opens source code they have a team of lawyers that have solid legal arguments for what the copyright year should be in each case.

Therefore, maybe it’s even possible legally that

3. Even if source code was previously made available, and even if no changes were made in any way since then to any of the included source code or other files, perhaps just the act of using a different license is in its own way part of how copyright applies. Publishing something under a specific license in $CURRENT_YEAR does not retroactively make the license apply before the time at which it was made available under that license and so perhaps an argument could be made that copyright year in a license includes taking that into consideration.

> IANAL but copyright is typically the year of first publication.

Under current copyright law, copyright is effective from the moment the work is first set in fixed form, though I think copyright used to be based on first publication.

Updates creates a new work, for which the copyright date is that of the updated work being completed (which doesn't change that some parts are also part of works copyrighted earlier and which may enter the public domain earlier.)