This was really fun! The momentum-based movement made this almost like a puzzle game, trying to figure out the best use of fuel to get to the next checkpoint. I also think making shooting cost fuel was a great idea, as there's now another action you have to balance with fuel consumption. The exploration theme is also very strong here, in trying to get upgrades to buff your hull and fuel capacity. I ended up getting all upgrades and finishing in about 8 minutes, dying a few times in the process.
I think the momentum gameplay worked, though personally I found the ship to be a little too heavy when trying to changing directions. There were times when I spent a bit of fuel in the opposite direction I was moving, and found it to barely change my velocity. Maybe that's part of the design, but a slightly lighter ship would make this feel better to control, imo.
Really excellent job on this, I thoroughly enjoyed playing your submission! And it's awesome you have the source code available too, for others to see.