Echo Deep

Pilot a small submarine through dark underwater caves where the walls stay hidden until you click to send out a sonar ping. For a brief moment the cave lights up and you can see the rock around you, but every ping carries sound through the water, and the fish hear it. They turn and swim straight toward you, so each flash of light is a trade: safety now, danger a few seconds later. Your job is to collect pearls, keep your distance from the fish and find the exit before the cave closes in on you. When the fish get too close, throw noisy buoys into the water so they chase the sound away from your submarine instead of toward it. NAJOX adds twelve levels that slowly raise the pressure, with currents that push you off course and jellyfish drifting through narrow passages where there is no room to turn. Between dives you can upgrade your submarine, improving how it handles, how far your sonar reaches and how long the walls stay lit. Every level asks you to plan your pings, read the darkness and decide when to stay quiet and when to make noise.

Move the mouse to steer. Click or press Space to send a ping. The ping shows the walls, pearls and fish. Right click or press E to throw a buoy. You can also move with WASD or the arrow keys. On a phone: drag to move, tap to ping. Collect enough pearls, then swim to the exit. Fish hear pings and fast moves. Near fish, move slowly.