To begin, wow, this game is amazing. I have enjoyed UnderRail more than any other game since Fallout New Vegas. Thanks so much for making it.
That said, I see you have a place for suggestions, and I do have some, sorted with most important at the top.
Default walking speed should be faster. There's a LOT of walking in UnderRail. If upping the default walk speed means movement enhancers have to be adjusted, go ahead and adjust them, whatever is needed to let you get around at a faster rate out of the box.
Inventory managment could be improved. There's a LOT of inventory management in UnderRail. If the Split command automatically let you type in a number and hit Enter to split to a quantity, that would be very good. Also, could we get a sort by different traits, like stack weight, value, type, and current shopkeeper purchasability? Instead of just "Sort", have "Sort: W V T S". Especially in the early game I really wanted to be able to sort by weight.
Having a toggle that allowed you to hide weightless quest items and get them out of your inv screen would be nice. I'm (guessing) half way through and I have quite a collection of these now. Maybe simplest way to implement this would be to add a new inventory filter "Everything Except Plot Items" and make it the default.
I like the way fast travel is handled in UnderRail. But there should be more of it! Maybe in Core City there are jitneys at the docks and the metro station who will take you to your house or the Arena or [...] for a small fee. Maybe Foundry has an ore cart trolley system that connects different bits of the town.
I think the crafting interface could be improved. I'm not sure what the best route to this is, admittedly. Maybe a sort feature that lets you sort recipes by Alphabetical, Most Recently Used, Carrying Complete Ingredients For (then alpha)?
The quickbar with shift and ctrl for alternate panels works pretty well. I don't really mind it. But I would have found it more intuitive if there was one key that rotated through the different panels. This would allow for more than 3 panels easily, if that was wanted (3 seems enough to me, but maybe it won't be for UnderRail 2).
I agree with the other suggestion that Auto trading within SGS should use up SGS credits first.
Default font could be bigger. Does UnderRail phone home with player behavior stats? How many people took the trouble to adjust the font size. I bet a lot. Probably an artifact of 7 years of dev time starting on smaller monitors...
Again, thanks for the great game. Have bought copies for friends and family and probably will buy more. I hope Stygian Software gets the recognition and $$$$$$$ that it deserves and this is only the beginning.