Regarding an in game tutorial: Originally we were going to include something of the sort, but we ran out of time in a rather drastic way, and there wasn't any time left for anything that wasn't a part of the core gameplay - so we had to settle on explaining the features on the itch.io page the best way we could. I was very tired back when I wrote the instructions, so sorry if I didn't make the mechanics too clear...
Yeah, the bullets only being able to be parried while focused is a feature. Seemed like a good way of balancing the parry mechanic, at the time - although now I'm not too sure.
Glad you enjoyed the game!