Dev intentionally attached in-game pictures to this game that arent included in the provided download / build. That is misleading. Thanks for trying tho
Like with most game threads on this site people/ Devs only add in the pictures when the thread is created. That is why, if you where to check, many of the well known games/ projects still have the same pictures up on their front page they had on day one. Even tough there is more/ different content in those games now they do not remove/ update those pictures because either
A: The pictures still represent what the game is supposed to look like/ be about.
Or B: The version of the game that is available here was pirated and put here without the consent of the Dev, managed by a mod, that only updates the game files when there is an update.
They did not try to mislead you, you just want to feel mislead. As you said yourself:
i finished all the quests and got the popup "end of demo" and none of the dancers or nemesis or whoever falls me into that other room.
You played a DEMO, something that is supposed to give you an idea of what the gameplay will be like, when the game is finished and you decide to buy it. It is common sense not to expect to get to play the whole ass game in the demo and see all the places that are shown in the advertisement for the full game.
Again, no one else is trying to mislead you, but yourself for not making that connection.
So calm down and have a nice day.