While we all wish it was easier to edit the assets in my new games, Steam Workshop is finally here to at least make it indirectly possible! You can now "subscribe" to a whole range of mods and have them automatically show up in your game by choosing the alternate "Play Modded" launch option:
https://steamcommunity.com/app/1620340/workshop/
Not only is this easier for users, but it's also fairer for the developer if all of this happens within Steam - where paying customers have earnt the right to customize a game they supported to this point. Once you get comfortable with it, you may even find yourself uploading your own mods! Look out for a couple of new PDFs explaining each side of the process. If enough people support the content, it could become a mutually beneficial way of breathing new life into the game for years to come. May I take this opportunity to publicly thank IngoH for his tireless efforts in taking us this far.
If you know this is never going to be your thing, you can revert back to always launching the vanilla version with a quick tick of that box. This is by no means my way of giving up on the project, as I have plenty of official developments in the pipeline as well.