Congrats on publishing your first Godot game, it's very well done! Nice visuals and music, it's quite enjoyable.
The gameplay is simple, but it's a good idea. It lacks some balancing though, as whether you win or not is very random and depends on your luck regarding which planets will spawn where. I often had playthroughs with only planets at negative deltaC so I would run out of energy before reaching any that could recharge me.
I also found it weird that the actual movement speed changes based on thresholds. It would be much better to make it proportional to the speed magnitude displayed in game, to avoid having big slow-downs/speed-ups each time you reach a threshold.