Great game! I am on Day 52, and I am sort of getting the idea that it will not get more difficult, and scenarios will stay the same from then on. I wish that there were more enemies and things you can craft in the game, as the turrets I have get the job done easily. Other than that, I actually found this game sort of... addicting? It is a great time killer!
ADVICE FOR NEWBIES: Get ALL of the iron ingots you can and save them for repair kits. If you want to make a new turret, but your train is in the 300s, do NOT make the gun. I cannot stress this enough. If it is difficult for you to shoot and aim at the "birds" at first, iron will be your best friend. At least keep the health of your train in the 700s, and if you have enough iron to create a new gun, go for it. Just do not use them when your train is near broke.