First off, congrats on your first jam!
I've just come off a streak of reviewing games that don't really work properly - so this was a really nice palette cleanser for me 😀
Art is, obviously, awesome. Extremely diverse and visually interesting. The character's, monsters, and the train itself all look awesome. This is one of the those games that it's very easy to take interesting screenshots of. Background music is good. Catchy little ear-worm that doesn't get annoying.
The gameplay loop is quite compelling. I like these kinds of high-stress, active management games a lot. There are a lot of places you could take this concept, which is one of the ways you know you have hit on a decent jam idea.
I think there me be some kind of bug with assigning character's to the shield generator and fires, as sometimes the shield bar didn't increase any faster with someone assigned to it and sometimes fires just kept going no matter what I did.
Nice work friends!