Final score: 17:20
This game was very satisfying once I got going. I thought I'd stumbled upon some incredibly busted combo, but looking at your gif, it looks like that's very much gameplay as intended. After a while it did get to the point where it felt like there wasn't really enough to actually do between upgrades, though pumping "w" while watching a birds' nest of lines cover my screen was very zen. It didn't look like any aliens were getting through, but I guess they were, as my health bar did slowly drain at the end. I wasn't sure what circumstances caused the sudden slowdown of the train, but I was able to circumvent it by pumping the engine instead of holding it down.
I know game jam constraints are what they are, but I'd love to see this game get revisited to have more content, so that it doesn't feel quite as repetitive at the end. On the other hand I drove in circles for 17 minutes, so.......