itch.io

Welp, as also one who experienced it as well, again it's the engine problem,  all I can recommend is to watch the videos, which are on the movie folders, and/or then make the videos one second (by video editor/video converter) to skip the sequence entirely, which will allow you to get to the remainder of the game. Make sure to backup the movie files if doing so.

The trick to fix that is just do one full playthrough and not get any of the other endings prior. Except the true end or the game will break  then you'll unlock the secret ending.