Good game, the shooting feels nice and movement is alright. The biggest issue I had is the time relativity when going to the other side. If I stand still and go to the other side to avoid a boulder, wait a few seconds, come back to the first side, and the boulder is in the exact same position, apparently I have to walk through the boulder after I shit, which isn't what I expected since I am on a moving train that should move without me moving.
Also, you have two tutorials, one labeled "tutorial", the other "how to play", I think you should only have one. In the "Tutorial", the text disappears too quickly for me to read, which made me restart it in order to read it all.
Overall, great game, just perhaps improve the time relativity between both sides and it would be better.