Overall a very unique and original concept with a rather abstract style of gameplay.
Now before I get into my feedback on the game. As this game is expanded on from a prior jam submission rather than being an original submission; I have rated it to a higher level of scrutiny than I would the other entries. Overall the game does deserve its praise, however as I do my best to be fair, it is only fair to factor in the longer development time when scoring.
First off, the idea of being bound to a train both as your combat arena but also a way to avoid certain attacks is ingenious. However, from the levels I played the only times I needed to hop inside was when I felt overwhelmed by attacks and needed a short break. It'd be interesting if there were more engaging reasons to hop inside in-between dealing with the main adversary. Perhaps in some missions there could be timed bombs on the inside that need to be periodically 'defused' so you can't spend too much time outside, you could even have certain attacks come in through the windows to make this harder.
As for gameplay, whilst it does feel very polished, due the whole limitation of being locked to 3 sides of the train it can be difficult to maintain a lock on the enemy whilst avoiding attacks, especially when they go underneath. In addition some of the attacks were hard to judge their distance from the train and I would often just walk into them by accident. Ok on second check, the lasers do turn white when near you, and knowing that does make things easier to judge however maybe try a different colour as the white/pale blue beams blend into the framework of the train which actually makes them harder to see at times.
As a small suggestion, a defensive ability like a shield or something similar would go a long way to improving engagement outside of just hold left click on the enemy whilst dodging; even if it then needs time to recharge. You could even go a step further and have certain projectiles which can be deflected back at the enemy.
Lastly, the stormy level (the red card) needs a look over in regards to optimisation as that level caused my old but reliable gaming laptop to drop into unplayable frame rates despite the game running butter smooth on every other level. Ultimately I had to skip this level.
Nit-picking aside, the game is well made and fun to play. With few tweaks here and there to refine and polish the experience, and you could have a rare gem.
Also just had to ask, but what is the purpose of the coins under your health? They are positioned in a way that makes them seem important but I couldn't figure out how or why.