I like various thoughts such as ones on YouTube about difficulty, and many others about how Dark Souls 2 and other games allow the players to set their own difficulty as opposed to menu item of "hard, medium, and easy."
Being able to dock both the Prawn and Seamoth would be great for a next level sub. I also would like energy generation, and water purification abilities.
Should Kyanite be needed to build this to where it is aimed at end game content?