It's not real at all.
In a real submarine every officer and every man has to go through months of training, both in classrooms and aboard ship. You drill and train until you know exactly where every instrument and every switch is located, at least in your department.
Look at your Flight Simulator. To truly simulate the cockpit you would have to have a game console that was an exact copy of the cockpit, with all the real gauges and switches actually working. Then you could develop the muscle memory to instinctively know what to do in most situations, and hopefully in every situation. This is how an air force or airliner simulator works. In the game you use the mouse to flip certain switches, something you don't do in real life.
The same is true of the ship. To be a true simulation we would need the complete mock-up interior made for
Das Boot, with one of us being the captain and everyone else doing their job, coupled with video graphics plugged into the periscope and a full surround screen for the bridge, along with appropriate smells. I know that sounds silly but smell is a major part of life and all our experiences.
The captain gives orders to different personnel, and if they've trained together properly they know not only what to do and how to do it, but what he wants and how he wants it done. The game is a simulation, but it's not a simulation of reality, but of how reality
feels. Does it make me feel like I'm really there? Does it make it easy for me to pretend I'm really stalking an enemy merchant ship? Does it make me feel like I'm actually sailing through the harbor, with the sights and sounds illustrated as I imagine them to be?
If so, then it's doing its job.
