I wonder if it would be possible with ebook tech (probably with epub?) to make a book that changes as you read it. Like, a short book that's about a stable time loop, where at the end of the book they end up causing the events at the beginning though time travel.
but if you read it again, things are different. the stable time loop isn't so stable. they remember things from the previous iteration, but things eventually end up the same.
the next time, it's more pronounced. things go massively off course. they aren't sure why, but everything seems familiar. the timeloop gets triggered again, but only barely, and only because of a fight between the different sides, some of who want it to continue.
the next time it's clear from the beginning that it's a time loop. the other side tries to trigger it early, the protagonists attack immediately, knowing what happens. the time loop is prevented. there's a considerable epilogue, they retired and grow old and happy.
then it starts over again anyway. they didn't fully destroy the enemy, the time travel tech still existed, this iteration of the timeloop just went long.
the final time, the battle is decisive. many are lost, sacrificing themselves to stop the time loop. after all, if they fail, they'll come back. if they succeed, they've escaped this endless torment. the enemy is completely destroyed. the time travel tech is eradicated and the knowledge of how it was built is intentionally lost. the survivors spend their remaining days ever vigilant for anyone trying to revive the time loop. but it ends, with no time loop triggered.
you open the book for the last time. "Chapter one: It was a beautiful day, and everyone was happy."
You turn the page. It's blank. So are the next 200 pages.