Do you want to learn Morse code in a submarine setting?
If your answer is anything other than "wait, what?" then here's the game for you. Just give it an hour or two and you'll be able to encode letters and form words with ease... as long as you don't forget about it the next day. Sadly, the game doesn't open up far from it but it still has the potential to do some quizzes and much more with a DLC.