Your high school physics teacher weeps.
You fail physics forever, my friend. It was a good game, yes, very good... But...
GRAVITY DOES NOT GET STRONGER THE HIGHER YOU GET!
Gravity does not pull things against the surface of a planet. It pulls them towards the core. Gravity gets WEAKER the farther from the center of an object you go - that's a constant fact. You should, if anything, need the antigrav coil at the start, not at the finish.
You Fail Physics Forever.