Thinking what to write feels good, actually.
It's a diffrent way to solve puzzle by writing.
It'll be game if you add some sound effects and musics and also expand the story and world.
I think when we type wrong command, the game warns simply by text. Because otherwise command line looks very crazy when we type so many wrong commands.
Also i think when we press a button like TAB the game complete the important words automatically. E.g. In the coffee room: if we wrote nothing and pressed TAB, game would type drink.After that If we pressed again, game would type coffe.(We use it only when we stuck of course.)