Do we want to end timing on the last input or the closing of the curtains? I always personally thought it was last input.
They're about 0.3-0.4 seconds apart, and we don't have it documented in the rules.
(Also, I just added mcill as a mod.)
I never really cared about end timing because I thought in-game time took priority. IGT has always seemed accurate to me, with RTA being 1-2 seconds slower (because of accidental pauses?). My final splits are never accurate anyway because I'm too busy trying to spam through the text to split properly.
My preference is to go with last input for the final split but with IGT being the important number. RTA can be a tie breaker if people don't like sharing.
I think IGT counts pretty much every frame except the cutscene at the beginning that you have to hit escape for. It seems to stop either at last input or the curtains, not sure.
IGT primary with RTA on last input as a tiebreaker seems fine. It makes my run 6 seconds faster because I didn't hit escape, not that it really matters in the scheme of things.
I have always been of the belief that if a game has an ingame timer, people should attempt to use it if possible, unless it is proven to be unreliable, inaccurate, or otherwise unsuitable for competition in some way (then use RTA instead). This game applies for that, where the clear time on the end screen should be perfectly fine for leaderboards. In terms of RTA I always ended my split on the same input as pressing Yes to marry (I set my split button as Start on my controller so I could actually do both with 1 input, same as starting the timer on the file screen).
I don't like RTA as the main timing method for this game because it would involve fighting for frames to skip the cutscene as early as possible, while affecting no other part of the run.