Tidewalk

Tidewalk is a living reef in your iPhone, and your daily steps keep it going.

Clownfish, angelfish, a flame angelfish, a blue tang, a yellowtail damselfish, a royal gramma, a clown triggerfish, a picasso triggerfish and a moorish idol swim around their anemone, a mandarinfish potters about on the reef floor, a coral grouper lies in wait, and cleaner shrimps keep a cleaning station where fish come by to be cleaned. Tilt your phone and the water stays level, like in a real tank, or tap once to look down into the reef from above. Tap a fish to meet it: every fish has a name (which you can change), an age, a partner and maybe young of its own. Hold a finger on the glass and a curious fish swims over to nibble at your fingertip, or double-tap to knock on the glass and watch them dart away. Now and then a sea turtle, an eagle ray or a barracuda passes by in the distance, and once in a while a great white cruises by just under the surface. The sky above changes with the time of day, from blue with drifting clouds to a warm sunset and a starry night.

YOUR STEPS RAISE THE TIDE
• Today: every morning the tide is out and the water is hazy. Each step brings the water up and clears it. Reach your goal and it's high tide, with clear water and fish at their liveliest. A walk in the evening counts as much as one in the morning.
• Good days: reaching your goal brings gifts. The fish get a feeding, a visitor swims by, and the reef's couples raise young. And the Aha-fish comes to visit: a beautiful fish with a heart on its flanks that only shows up on days you reach your goal, and swims off again overnight.
• Weeks: as good days add up, new species move in one by one, and coral grows on the reef floor, a piece for every good day. In Fish Challenges you walk for the fish you want: pick one, take on its walking challenge, and a pair moves in when you've done it.

A LIVING SOCIETY
Fish of the same kind pair up, swim together as couples, raise young, and now and then split up. Fish live for a couple of weeks and are followed by the next generation. The reef is wider than your screen: swipe sideways to follow the fish, and it grows wider as new species move in.

No streaks to protect. On a missed day some pollution may drift into the reef: a bottle, a tyre, an old fishing net. On your next good day you can tap it away, and no fish is ever harmed.

GENTLE BY DESIGN
• A calm sea sound, which you can turn off with one tap.
• Set your own daily step goal, and change it any time.
• If you like, one reminder in the afternoon while the tide is still out, and a note when you reach high tide. Never more than two a day.
• A widget for your Home Screen and Lock Screen shows today's tide at a glance.
• Works with your iPhone's step count, an Apple Watch, or any watch that syncs its steps to Apple Health.

PRIVATE
Tidewalk reads only your step count, and only with your permission. Your steps and your reef stay on your iPhone: no account, no ads, no tracking, and the app makes no network connections.

Tidewalk is a motivational game, not a medical device.