'Twas definitely the number of table entries that were lists; zarf explained to me that every single list had to have memory space reserved for it on the memory heap (if I’ve got that terminology right). The game more or less entirely consisted of tables that had a list-valued column; I think there were fifty or sixty lists all told.
@Dannii: I see that 21.2 has some pretty misleading language about “let” vs. “now”:
On the other hand, writing
let M be { };is fine provided that M already exists, and then does the obvious thing - empties M.
This is only fine if M was created as a temporary variable in the same code block. If M is a global, then you’ll run into the usual issue where Inform tries to create a separate temp variable named “M” (and in this case, it will fail because it doesn’t know what kind of value is in the list). In general, for whoever is listening and needs to know this, setting the value of an existing variable should always be done with “now” and not “let.”