- It would help clearing the window after an invalid input (maybe with a "Your last input was invalid"), too many of them can clog things up and force you to scroll up.
- There's no help/h/menu command, thankfully your screenshot showed how to attack.
- Again, I would've preferred the window be cleared after a turn, to keep the screen tidy (if you were avoiding to do so to have the history of the combat you can add a show combat log action).
- A 0 + anything that's not a digit + anything is strangely being accepted as an attack command.
- You should show the battler's hp when you print info about the current turn.
- After a while (at the end of the battle I assume) the window closes, I would rather showed a simple "won/lost. play again/quit: " prompt.