First off, the way you start your description is amazing!
A couple things I would say about the game play: the character tends to get stuck on the sides of platforms. You may be able to fix this by setting the friction of the character to 0. Second, when you respawn, you respawn with all your momentum so it would sometimes just fling me into the spikes a second time immediately after respawning.
The concept is cool, I like how you have to learn to time your jumps correctly to the hidden timer so the gravity switches at just the right time, the art is good, with a bit more work, this could be quite a fun game!