Submarine based on the game "Iron Lung"
There is no airlock so you have to cut a hole in the sub if you want to leave, you have 30 minutes of battery life for full power consumption, driving is done through sliders via the power distributor menu, no oxygen generator so get used to switching tanks using the oxygen tank holder. Oh yeah you can also only see your surroundings with a 9x9 array of lights that can only be on for 5 seconds before a cooldown.
Good luck.
