I'd played the demo on Steam last week, then bought this on Itch. Had a good time with the old version, and am having fun with this version. Great game.
But here's a heads up for anyone playing the current version from an incomplete old version save (still have recipes/letters to make). The factories show the letter/non-letter combination before you hit play if you've made that character before. If you've never made the character, it'll show a blank. A blank is also not an invalid combination; that's still a question mark.
Spent about twenty minutes trying to work out a way to make the letter F because all of the combinations were showing a blank. So, hopefully this helps if you're playing an older save.