In Phantoms Deep, the control sensitivity panel can be opened at any time during play by pressing Escape or the three-bars/menu button on Steam Deck. The available sensitivity range is intentionally very wide to support many mouse resolutions and player setups, so most players should expect to spend a few moments tuning their personal feel before diving too deep. Sensitivity settings are saved between sessions, so once adjusted they will remain in place. Viewing, periscope, and sonar/turret controls each have separate sensitivity settings, and the checkbox on the left shows which control mode is currently being adjusted.
The Graphics panel lets you adjust performance and brightness while the boat is underway. The easiest setup is usually to set the Target Frame Rate as high as possible and leave VSync alone unless you specifically need to reduce screen tearing. VSync and Target Frame Rate are meant to solve similar timing problems, so you should generally use one or the other, not both: VSync locks rendering to your monitor’s refresh rhythm, while Target Frame Rate sets a manual FPS cap. The Gamma setting adjusts the image brightness, especially the mid-tones, making dark areas easier to see without simply flooding the abyss with light. Use it to tune visibility for your monitor and room lighting.
The Game panel contains general gameplay options, including quitting the session, multiplayer access, and First Mate Behavior. The First Mate can be set to one of three modes: All Stations, where the First Mate is allowed to control every station; Reactor Only, where the First Mate only manages reactor-related controls; or Disabled, where the First Mate does not assist at all. This lets players decide how much help they want from the boat’s loyal metal-scribbling assistant while they manage the deep. The Invite Friends button is visible, but it is not currently working. To join a friend, start the game, choose Join to open the Steam Overlay, select your friend, open the dropdown menu, and choose Join from there.