That's where the first of my nitpicks comes in. You can only give your train a preset color scheme (more being unlocked as you level up), and each preset comes with its own train horn. The only thing you can individually change is the color of the train's flags, which you barely, if ever, see during actual gameplay, although I will give the devs major kudos for having a bunch of LGBTQ+ flags among the options. Still, I do wish you could mix and match the color schemes and horns, or better still, custom color individual train parts yourself, as I found many of the preset designs a bit too similar to one another.
And while we're in nitpick mode, I'll get my other main gripe out of the way, and that's the map. Now, the map in and of itself is fine. Again, I like how you fill in the tracks as you go, and you can place stamps of varying designs and colors to mark points of interest, traffic signs, etc. You can place up to 250 stamps which is more than plenty; even after marking everything I could, I didn't even use half that many. No, my problem is that when on my way to a given destination, every time I came up to a junction, I was bringing up the map to remind myself which way to turn and for me, this breaks the flow of gameplay a bit. I feel a minimap would go a long way to alleviating that.
I also ran into a couple of issues - one gameplay related, the other more technical - which I hesitate to bring up as they might be problems, or might just be something I missed. During my runs, there will be plenty of times when I come to a split track with a traffic signal set to red, indicating you should stop and wait for another train to pass, but I'll check the map and either there aren't any trains anywhere close to me, or if there is one, it's heading away from me. And once, I had the opposite issue; I came upon and passed a green light...only to careen into a train at the next junction. I'm not sure if that's a bug or if there's just some quirk to the way the signals work that I'm not catching. Then on the technical side of things, when double-clicking the game's desktop icon to launch the game, I'll get this error message: