Played twice but didn't get how to unlock a different ending and also the movement speedup didn't work to play a third time. It was interesting, I really wanted to know more about what happened and how to unlock the other endings.
To use the speed up movement you need to press select (Shift) at the GBJam screen and you need to be quick since the screen doesn't stay for long. A tip of 2 of the endings is that you don't need to collect items for them. Nonetheless thank you for trying out my game!