Aces of the Deep is a simulation game released in 1994 by Sierra On-Line. The game was released for PC (DOS).
In the game, we play the commander of one of the seven German U-boats. Depending on the game mode chosen (single mission or career), you will perform a series of missions or choose one episode (eg destroying Allied convoys). In career mode you will earn medals and promotions that allow you to command better submarines.
You can set the level of realism freely, for example, you can remove fog, endless ammunition or finally turn on "immortality".