Fathom: Last Known Position

FIELD MANUAL

You're a lone submarine in hostile waters. Sonar is free intel — ping often and hunt down what it reveals, since sitting still doesn't make you any safer, the real threats come looking for you either way. Surfacing gives you a clear look through the periscope, but exposes you to gunfire. Survive escalating waves of enemy subs, destroyers, and hazards for as long as you can.

CONTROLS

W A S DThrust / rotate SPACESonar ping (underwater) Q / EPort / starboard tubes CSurface / dive A / DSurfaced: sweep periscope ESCPause

DEPTH STATES

Surfaced — look around with the periscope, safe from mines, but exposed to gunfire.

Underwater — your default. Sonar works here; mines and torpedoes both threaten.

DETECTION & SONAR

Ping (Space) every 3 seconds. Anything the wave crosses lights up briefly, then fades.

Surfaced, A/D swing the periscope only — your hull stays pointed where it was. Power-ups only show up this way, and stay visible for good once spotted.

Enemy subs ping too. Get caught in one and every enemy instantly learns exactly where you were standing — a static mark that fades after ~16s. Move fast and their shots land in empty water.

ENEMY FORCES

Enemy subs come in three sizes: small and medium go down in one hit, large takes two and visibly sparks once wounded. They have to actually turn and line up on you before firing — the large ones also carry a turret that doesn't need to.

Destroyers come in three types: minelayers drop mines as they cruise, drone carriers launch seekers, buoy layers plant pinging buoys. They only open fire once your periscope actually spots them — otherwise they're just patrolling hazards.

YOUR ARSENAL

Q / E fire port / starboard tubes, each reloads on its own timer.

Ramming an enemy sub can take it out in one hit or two depending on its size — either way you take hull damage too. Destroyers just bounce you off.

HAZARDS

Mines detonate hard if you drift too close, with a blast radius that catches anything nearby — ships, even other mines. Torpedoing one from a distance sets it off safely instead.

Homing drones, launched by drone carriers, arm on proximity and beep faster as a short fuse burns down. They keep closing the whole time — dive to break the lock, or get clear before the beeping runs out.

Sonar buoys, planted by buoy layers, pulse far stronger than a sub's own ping and mark you fast. They're stationary and destructible — worth hunting down.

SURVIVAL

Watch the hull bar — you'll get a warning at 50%, and zero ends the patrol.

Kills push the wave counter forward, and later waves throw more at you — heavier classes and more destroyers as you go. The map is big but not endless; wander too far and you'll feel a gentle push back toward the center.

Power-ups only reveal through the periscope and stay visible once spotted:

Repair Kit — patches your hull
Tracking Torpedoes — curve toward the nearest target
Longer Pulse — keeps sonar contacts lit far longer
Anechoic Coating — shrinks how easily enemy pulses, buoys, and drones can find you
Engine Overclock — a short burst of much faster thrust and turning

Active effects always show in the status panel with time or charges remaining.

CREDITS

Built by Evan Fruehauf for Nautical Jam 2026.