For some reason I got the idea that to “beat” the game you could attempt suicide, which would mean dying but not by Izanami. With the windows and doors being locked, the only shot would be something like jumping headfirst down the flight of stairs. If it’s just a game, then it should be fine, but if it actually kills you anyway… oh well.
However, since it’s shown that youkai feed off those that are driven to suicide, that might also be falling right into that trap.
What I found interesting is how Aya wanted a purpose to live, which Izanami gave for their game: to not die. Aya believed death was an escape from existence, but Izanami turned that around on her. By giving her a reason to fear death by Izanami and falling into his hell, he’s also given her a purpose to continue living. By figuring out a way to beat his game, she’s given a reason to continue living.
Seeing how the previous stories have went, I was expecting something negative to happen at the very end, like having her trip at the end or to stop short at the finish line because she finally had second thoughts. Something to turn it all around because Ryukishi can be so delightfully cruel. But she made it. It had a strong message in its story to tell and it wasn’t going to pull a cheap trick, it felt honest like Izanami.
I like how running is the main action. It turned from Aya escaping from her own death to escaping from an unfulfilling life plagued with questions that can never be answered and thoughts that hold you back. A life like that isn’t exactly “living” in the first place, it’s simply existing.
The solution Aya came across is to clear her mind of such questions and thoughts. We have the intelligence to recognize our mortality and the emotions to make us fear and avoid death. By being aware of life and death, we become aware of our existence. We question our purpose to make sense of reality because we desire fairness and balance, but reality is chaotic and unfair. And through our emotions and intelligence we experience suffering; mental anguish stresses the emotions and emotional anguish stresses the mind, and at times we trap ourselves in our own suffering. Through suffering, we try to make sense of our life and learn from it, even if we have to stretch the meaning of our suffering so that it fits in a way we’re satisfied with to cope with it.
We’re still only mortal so death is an inevitable fact of life. But, with how our minds work right now, even immortality in our current state is discouraging because we see suffering as a fact of life as well. But since we’re already alive and existing, our instincts drive us to preserve ourselves as much as possible, so not only do we naturally fear for our deaths but even the thought of losing our emotions and intelligence to relieve our suffering is also frightening because it’s what makes us human. We can try to make changes to our life, but we’re still powerless when we’re just one person against the world that’s against the universe, and we find that frustrating. So the best we can do to push all these stressful questions about life with answers we feel we already understand anyway yet dislike is to just… stop thinking about it. And live. No need to dramatically change who you are as a human being. It’s such a simple solution to something horrendously complex, but we like to overcomplicate the simple things - sometimes to where we miss the point and look at it differently.
I hope I didn’t ramble too much there. 
The youkai in these stories really are peculiar, fickle creatures. Higanbana hinted at the trick to Izanami’s game, Izanami’s offer of a peaceful afterlife was treating Aya as more than prey, and the two of them may have saved Aya’s life; saving it by helping her realize how much those thoughts were holding her down. Higanbana is especially fickle. Just as she could easily be denying Izanami his prey by helping Aya realize the trick, Higanbana could have genuinely been helping Aya for her sake.
