The problem here is that you’ve been emotionally wounded by this, likely because you put a lot of yourself into this game and it hurts to see the thing you worked so hard on fall short. In such situations, I find it comforting to acknowledge the good takeaways I have from the project. That might be knowing that players still enjoy the parts of the game I was responsible for, even if the overall experience missed the mark. That might be valuable lessons I learned so I never make those mistakes again.
Unfortunately, understanding that there was nothing you could realistically have done probably won’t significantly soothe the emotional damage you took from putting your feelings into your work on the project, especially if you had seen it coming and tried to warn the decision-makers. The passenger in a car wreck might have had some responsibilities like choosing the music or helping with navigation, but no one in the world could realistically place blame on the passenger for a car accident. You cannot blame yourself for the results if the responsibility was never yours to begin with.
Like any wound, emotional injuries take time to heal. Things will eventually get better with distance and time. You medicate the pain as you need by distracting yourself in the short term with whatever helps take your mind off of things. Give the wound time to heal and get the kind of closure you need. I promise it will get better over time. I encourage you to check back in with me in a few weeks.
Got a burning question you want answered?