Thanks for the feedback and playing the game. We will work on the controls and add instructions since a lot of people have pointed that out. The game over screen is because the time ran out before you completed the repairs and the sub imploded (as it says on a note in the bridge room). As for the keys, F is for using items in your inventory, and E is for interacting with objects (for example: F to use key and unlock door, then E to interact with door and open it). We'll try to make all these things more clear in next patches.
Viewing post in Echoes in the Hull jam comments
yes I figured it out but I just think you could just either a) use f on the door with the key and leave the room, or have the door at least open so you dont need to press another button to exit the scene - you can just walk through, or b) use E and because you have the key the door opens - this sort of thing. Let the player press Enter to close a text box instead of clicking the mouse for example. These are small things that will get players to think more about the game and less about the controls they need to use to play the game. But its got lots of potential to be a great adventure game so Im wishing you all the best for it and looking forward to your next patches.