After endlessly wandering from one location to another, I finally discovered the text file called answers.txt in the installation folder, which contains the answers to the questions to get into the tower. I guess this was some kind of copy-protection thing? Or is there some way to get this information in-game?

I wish there had been a warning about this, perhaps after installation or in the game card on the store. Not that I mind using a walkthrough once in a while (for this game it seems it's going to be quite a few "onces" in a while), but in this case the external source is the solution.