I'm looking for a novel, of which I'm remembering mostly the end. It might be important that I've read the story in German.
Most of the story takes part in a strange, surreal world. Towards the end it is revealed that the protagonists are on a spaceship and the story took place in a virtual reality generated by an artificial intelligence to entertain them during a long term travel. It was so real that they do not realize most of the time that they are in a virtual reality. Over time, errors accumulate and the simulations stop when people encounter too many of them.
There is a mythical figure mentioned several times (I guess it was something like "Der Wanderer", which roughly translates to traveler or wanderer).
It turns out that the whole crew is already addicted to the virtual reality, only one of them resists. All but this one get back into virtual reality.
The final scene: The one who resisted the virtual reality has a appearance of the mythical figure, which asks him what he wants to be. He answers he wants to be a plant in the desert, just feeling the sunlight and the live flowing through his body. The mythical figure tells him "that's how it plants feel", and he opens an airlock.