LINE END: Cave Diving Survival

Explore flooded caves with nothing but your air, your line and your light. A side-view 2D exploration game. The first three caves are free.

■ Get back before your air runs out
Use a third of your air, then turn back — the real rule of cave diving, turned into play.

■ The line is your only way home
Lay line from the entrance as you go. Kick up the silt and even your light won't help. If you can't see, hold the line and it will lead you out.

■ Go where no one has been
The line you lay becomes your survey map. Be the first to reach a place no one has ever seen.

■ Dangers from real caves
Bad air in air pockets, ceilings loosened by your own bubbles, outflowing and inflowing currents, haloclines and white hydrogen sulfide clouds, nitrogen narcosis in a deep shaft, decompression stops on the way up, gear failures and tangled line. Beyond the sumps lie dry caves you stoop and crawl through.

■ Water and dry-land skills open new ways
Underwater: sidemount, pulling yourself up a fierce current, crossing long passages on a scooter. On dry land: climbing a rope up a shaft, free climbing, squeezing through gaps too low to crawl. Learn them in training, then go back past the places that turned you around.

■ No turning around in a crawl
In low crawls you can't turn around — to go back, you back out feet first. Go head first into a hole that drops away, and you can't crawl back up. Brush a loose block and it pins your leg; after rain, the water rises at the bottom of the hole. Fears taken from real accidents.

■ Rig your own rope and descend
Drop a stone down a shaft and listen for how deep it goes. Tie your rope to a rock horn and climb down: that rope is your only way back.

■ The weather changes what you'll find
A pillar of sunlight in a shaft, only on clear days. An underground waterfall, only after rain. Now and then, meet eyeless fish or a ceiling of glowworms.

■ Cold water, hot springs, tides
Stay too long in 6°C snowmelt and your hands go numb. In a volcanic cave's 41°C water, heat builds up inside a drysuit. In a blue hole connected to the sea, the tide reverses the current, so check the tide table and pass at slack.

■ A flooded mine, a lava tube under the sea
In a flooded mine, straight tunnels stack on three levels, all alike, under rotting timbers. A volcanic lava tube runs 300 m out under the sea, too far to swim there and back: take a scooter or a rebreather.

■ Dive with a buddy
Talk to your CPU buddy with light signals. If they run out of air, share yours on the long hose. Every cave has a rescue mission: bring air to a stranded diver and lead them out.

■ Special missions
"Three Overdue": three club divers wait in air pockets down different branches, lights turned low. When they see your light, they wave theirs. Bring them out one at a time.
"Before the Water Rises": rain has flooded the entrance. About seven minutes in, the low gap on the way out goes under. Who do you bring out first?
"No One's Line": no one has laid line here before you. The far end is about 220 m in, so push deeper over several dives.

■ The bubble-free rebreather
It scrubs your breath so you can breathe it again: gas lasts about five times longer, whatever the depth. But oxygen sensors fail and scrubbers run out, so be ready to bail out to your back tank.

■ Every accident has a cause
When things go wrong, an accident report traces what happened. You keep your experience and dive again.

■ Badges and an ending
45 badges to earn, and an ending beyond the far end of every cave. Save your survey maps as images.

• 14 caves, each with its own reason to dive. They get harder as you go
• 3 special missions, apart from the 14 caves (they open once you reach the far end of two caves)
• Shop and maintenance, gear upgrades (5 kinds × 5 levels), skills and jobs
• A step-by-step tutorial
• The first three caves are free. One purchase unlocks the other 11 and the 3 special missions for good
• No ads, plays fully offline
• English and Japanese