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I've been having some trouble with the ending of my current story, and I've decided that the best way to deal with those issues is to include a major twist. Due to the nature of this twist, I'm not sure if the reader will like it, or just be disappointed. Here's the scenario:
The basic plot of the story is that the main character is a prisoner on a planet ruled by intelligent robots with advanced technology. It's not as unoriginal as it sounds. The character gets unintentionally teleported to a different planet, in a different time. It is important to note that this story is a fan fiction based on the story of a game, and this event is part of that story, and therefore thoroughly expected. This is not the twist.
Following the general story of the game, the character goes through several battles and missions on this new planet. He meets characters who change him, and the way he sees things. He realizes some things about himself.
While on this new planet, the character has one goal: to get back to his home, and the woman he loves. However, he eventually learns that the people on the new planet need his help, and that leaving them to achieve his goal would be selfish. He has decided that that's something he cannot do.
The trouble is that there are now two stories on two separate planets. For story reasons, they cannot cross over. I cannot, for example, bring the woman the main character loves to the new planet, or vice versa. I can end the conflicts on the new planet in a climax, and then send the character back, but the climax will have already happened, leaving everything back on the home planet as feeling like extra (there is a separate climax there as well, but it consists mainly of dialogue).
I have decided that the best way to deal with these problems is with a twist: just before the main character would have the final battle with the antagonist of the new world, everything goes black. He wakes up. It turns out the whole thing was just a matrix-like simulated test the advanced robots were running on him.
This certainly fixes the problems. The unresolved conflicts of the new world don't matter because they were never real. There is only one climax, on the home world.
There's only one question: will the reader think this is a great twist, or just be disappointed that all they were reading before that actually never happened?
The character has learned things. He has changed due to his experiences. But those experiences never actually happened. The people he met never existed. Perhaps most importantly, the climax which everything on the new world was building up to never happened. It is true that the protagonist's main goal of getting back home never changed, and that he spent the majority of his time on the new world trying to get back. It was only at the end that he became invested in the war on the new world, and decided he had to stay. Nonetheless, the reader was expecting a fight to the death on the new world. That fight never came.
So that's my question: is there a way I can make sure a major twist isn't disappointing? Is there perhaps a list of do's and don't's? Of things to watch out for maybe?
Note: This cannot be answered by this answer. That answer explains what a twist really is and how it really works. This question is dealing with whether or not a twist of the kind I have outlined above will disappoint the reader. The two questions are similar only in the respect that they are both about twists. In all other respects, they are completely different questions. You could say the linked questions deals with how to create twists, while this question deals with how to prevent the reader from feeling like he's been lied to when the twist is revealed.
Further Note: After due consideration, I have decided that the answer here is in fact the best answer. It doesn't directly answer this question, but one can infer from it that to make a twist satisfying, it must twist back to the most emotionally satisfying storyline, and the twist itself must be more emotionally satisfying than what would have happened without the twist.