Nice game. But there are some problems. Firstly I think you should zoom-in only when holding the right mouse button, not toggling. And i have noticed a few missing colliders, two of which are next to the train. The particles that appear when shooting at a wall are also not really fitting for the game in my eyes.
You can actually turn off toggle aiming in the options, I agree playing with it off as well. The collider issues were fixed but then I broke my last version. I'll fix those along with various improvements in the next version.
I agree the particles should be more toony, they are placeholders for now. Thanks!