[fbelzile]

Check out my app: https://getcoldturkey.com/writer/

It looks a little like Word, and there's no new line box, but it has the other things you mentioned. You can also set it to block everything else on your computer until you write a certain number of words, or for a certain amount of time. I'm adding typewriter scrolling soon too.

The pro features let you disable certain keys, etc. but you get a lot of value out of the free version.

[eykd]

This looks great. I wouldn't have guessed typewriter-mode from "advanced key controls". For my use case, I needed to disallow any going back and editing. If Cold Turkey can do that, you may have yourself a new customer. :)