I knew that many of @zarfeblong 's games' source code was on the IF Archive. But I only just learned that his website has the source for all his #Inform7 and #Inform6 games (even, egad, #Inform5 games), and most of the others, save Hadean Lands.

This includes the new short IF game Advent Mirror.

https://eblong.com/zarf/if.html

(...except for I6 game The Space Under the Window, whose source was lost)