I know what you mean. The activation condition to reach the "end?" are rather abnormal. This has to do with the fact that it is an easter egg ending. I'm a huge fan of easter eggs, especially those which are really complex. It's for everyone who loves to solve riddles/hunt easter eggs.
I was very inspired by The Stanley Parable and also Antichamber.
You are absolutely right, the gameplay is linear. Especially if you compare it to The Stanley Parable (a fundamentality of The Stanley Parable is to have choices!) In future projects I'll try to pay more attention to giving the player more choices. Overall I want to focus more on gameplay.
There is a desire to further develop this project. I have a lot of ideas and a basic concept in my mind, but don't feel ready to start yet.
Thanks for your comment and feedback, I really appreciate it!
If I ever start developing, I'll let you know ;)