For a 10-seconds long rewind functionality, only 64MB RAM is needed (128KB * 50 frames * 10 seconds)
Users can stop rewinding whenever they want. They just have to press and hold a rewind button to play To reverse the game backward at 1x speed, users press and hold the rewind button. When releasedAnd at any point, releasing the button makes time goes forward again.
To avoid confusion, the display could get a sepia filter when rewinding, showing that time is moving backward.