Interesting concept, fun to play! Game feels good, but a few moments that get me kind of confused:
1) At some point - the train movements feels useless as there too much enemies on screen, that there is no way to escape
2) Some drones (especially rifle) feels much more powerful on start, but idk maybe thats how it should be
3) Kind of non-linear difficulty curve: at seventh wave it feels unreal to pass next, but idk that maybe normal for rouglike

P.S. Tried on web-version, and not the all of sounds change their volume by settings, some of sfx just stick to the maximum value