Support.

Every crab needs a shell exactly one size bigger than the one it's wearing. Swipe a crab to move it one tile. Walk it into an empty shell one size bigger and it moves in, leaving its old shell behind. Line crabs up in size order and one swipe sends the whole queue moving house. How to play, in Settings, explains every rule.

Each level gives you a set number of moves, shown at the bottom of the screen, and the tide bar fills as you use them. Run out and the tide comes in, and you start the level again.

Three undos per try are enough to fix a slip, but not enough to stumble onto a solution by trial and error. Every new try gives you three more.

Tap Hint to see the next few moves, which costs sea glass. After three tries at the same level, you'll be offered a free hint for it.

By playing well: solving levels for the first time, earning pearls, and setting off long chains. Sea glass can't be bought.

Every level has three: one for solving it, one for matching par (the fewest moves it can be solved in), and one for solving it without undoing.

All of The Rock Pool is free: 40 levels. One purchase unlocks the other five pools and their 200 levels, for good. There are no ads, subscriptions or timers.

Each pool's levels run from Dawn to Dusk. Later times of day, and later pools, open as you solve levels.

Go to Settings and tap Restore purchases. Make sure you're signed in with the same Apple Account or Google account you bought it with.

No. A purchase belongs to the store you bought it from. Your progress can move between them (see below), but the purchase can't.

Refunds are handled by Apple and Google, not by us. On iPhone or iPad, request one at reportaproblem.apple.com. On Android, use Google Play's refund page.

On iPhone and iPad, your progress syncs through iCloud between devices signed in to the same Apple Account with iCloud turned on. On Android, your progress and achievements stay on your phone. There’s no cloud save on Android. Use Move my progress in Settings to move them to another phone.

Go to Settings and tap Move my progress. On your old device, choose Send to show a QR code and a progress code. On your new device, choose Receive, then scan the code or paste it in. This moves your levels, pearls, sea glass and achievements, but not purchases.

Go to Settings and tap Reset all progress. This clears every level, pearl and piece of sea glass on this device and can't be undone. On iPhone and iPad, it also clears your iCloud save. Your purchase isn't affected.

Settings has separate sliders for music and sound effects. Slide one to zero to turn it off. Vibration has its own switch.

Moving Day follows your iPhone's silent mode, like most games. Turn silent mode off, turn the volume up, and check the sliders in Settings.

Low Power Mode limits how smoothly games can run. Turning it off, or closing other apps, usually helps.

No. Moving Day plays in portrait on every device, and either way up on iPad.

In the game, open Settings, then Achievements. On iPhone and iPad, they’re also in Game Center. Some are hidden until you earn them.

The game’s own list always has the achievements you’ve earned. Check Settings, then Achievements. On iPhone and iPad, if one is missing from Game Center, check that you’re signed in to Game Center.