Moat Boss Guide – How to Build Walls, Dig Moats, Beat Big Waves and Get 3 Stars on Every Tide
Moat Boss! is a free sandcastle defense game for your browser and phone. You are Pinchy, a small crab with a spade, and your job is to keep the sandcastle dry until the tide goes out. This guide explains how the water behaves, which walls hold, and what you need for 3 stars on all twelve tides.
Controls
- Work: hold the left mouse button (or your finger) on the sand. Pinchy runs to that spot and works there with the selected tool. Drag slowly to lay a wall along a line; stay on one spot to make it taller.
- Dig: the right mouse button always digs. On touch screens, tap the ⛏️ Dig tool first.
- Tools: 1 Build, 2 Dig, 3 Rock, 4 Plank (or the tool bar at the bottom). Q swaps between Build and Dig.
- Keyboard: WASD or the arrow keys move Pinchy, Space works where he stands, E digs.
- Enter (or the Bring the tide! button) ends the building time early. Esc / P pauses, R restarts.
How a tide works
Every tide starts with calm building time (35 seconds on the first beach, up to 50 on the last), then the tide comes in for 60 to 95 seconds. The sea rises for the first part of the tide, stays high, and starts to go out near the end, when you see The tide is turning!. Keep at least one castle standing until the timer runs out and you win.
Waves arrive every few seconds. On most tides every 4th or 5th wave is a big wave (every 3rd on Rogue Waves), about one and a half times as tall and longer. A BIG WAVE warning appears about three and a half seconds before it hits, with an arrow if it is coming in at an angle.
The water is real
The sea in Moat Boss is a real shallow-water simulation on a grid of sand, so it behaves the way you would expect at the beach:
- Water runs uphill only as far as the wave pushes it, then drains back. It pours through any gap in a wall and fills every low spot.
- Fast water picks up sand and drops it where it slows down. A wall gets thinner every time a wave rushes over or around it.
- Sand that Pinchy builds is packed: it washes away at less than half the speed of loose sand and can stand steeper. Soaked sand slumps, so a wall standing in the surf slowly sags.
- A castle loses health while water touches it, and faster water hurts more. The health bar above each castle turns yellow, then red.
Sand, walls and moats
Pinchy’s bucket holds enough sand for about three seconds of building. Digging refills it at the same speed, and that is the trick: dig where a hole helps you.
- Build a ring, not a line. Water flows around the ends of a short wall. A ring of wall all the way around the castle, about a body length away from it, stops water coming in from the sides when the sea gets high.
- Dig the moat on the sea side of the wall. It gives you sand and catches the thin sheets of water that run up the beach, so less reaches the wall.
- Taller beats wider for big waves, but the next wave will start eating the wall at once. Watch the spot where the last wave hit and patch it before the next one.
- Don’t dig next to the castle or under your own wall: the hole fills with water that sits right against it.
- Pinchy can work in shallow water, but water deeper than his shell that is moving fast sweeps him away. He tumbles, gets dizzy for a second and walks back.
Rocks and planks
Some beaches give you gadgets in the tool bar:
| Gadget | Where it shows up | What it does |
|---|---|---|
| 🪨 Rock | Gull Point onwards | A boulder that never washes away and that the puppy hops over |
| 🪵 Plank | Puppy Beach onwards | A driftwood barrier that turns itself to face the nearest castle |
Tap the sand to drop one. They can’t go on a castle or into deep water. They are best used out in front of a wall to break waves, or to plug the place where waves keep breaking through.
Seagulls and the puppy
- Seagulls circle over Pinchy for a couple of seconds, then dive at the spot where he was when they started. Watch for the shadow on the sand and keep moving: step away and the gull misses. If it catches him, it carries him off and drops him somewhere else on the beach, dizzy.
- The puppy is announced by a bark and a 🐶 arrow at the side of the screen. A couple of seconds later a corgi chases its beach ball across the sand in front of a castle and flattens every wall it runs through back to beach level. It hops over rocks and planks. Rebuild the gap before the next wave.
Shells and hats
Four shells lie on the sand at the start, and after each wave of the tide one or two more wash up on wet sand. Walk over them to collect them before the sea takes them back or they disappear after half a minute.
| Find | Points |
|---|---|
| 🐚 Shell | 1 |
| ⭐ Starfish | 3 |
| 🫧 Pearl (rare) | 10 |
Shell points add up over every game and unlock 8 hats in the Crab Closet: Sailor Cap (25), Straw Hat (60), Flower Crown (110), Cool Shades (170), Party Hat (240), Pirate Hat (330) and the Moat Crown (450).
Stars
| Stars | You need |
|---|---|
| ★ | At least one castle still standing when the tide goes out |
| ★★ | Every castle standing and on average at least 50% dry |
| ★★★ | Every castle standing and on average at least 85% dry |
Losing any castle caps the tide at one star. One star is enough to open the next tide.
The twelve tides
| Beach | Tides | What’s new |
|---|---|---|
| ☀️ Sunny Cove | 1 First Tide, 2 Moat Madness, 3 Twin Towers | Building and digging, then two castles and big waves |
| 🐦 Gull Point | 4 Gull Alert, 5 Rocky Shore, 6 Sideways Swell | Seagulls, rocks, waves that hit one side first |
| 🐶 Puppy Beach | 7 Good Boy, 8 Fetch!, 9 Sandbar | The puppy, planks, a sandbar with a gap in the middle |
| 🌙 Moonlight Lagoon | 10 Glow Tide, 11 Rogue Waves, 12 King of the Moat | Night waves that glow, a big wave every 3rd wave, three castles |
On tides with two or three castles, look after the one whose wall is weakest first. On King of the Moat the castles stand close together, so walls between them protect two castles at once.
King Tide
King Tide is the endless mode. After the building time the sea comes in and never stops rising, the waves keep getting bigger, and seagulls and the puppy keep coming back. Your score is how long the castle stays standing, and your best time is saved. Build the ring early and big, because there is less and less dry sand to dig as the beach floods.
Beach Maker
The Beach Maker lets you design your own beach: place up to 3 castles, 8 rocks and 8 dunes or tide pools, and set how wild the sea is (1 to 5), how long the tide lasts, how many seagulls and puppy runs there are and how many rocks and planks the player gets. You can keep up to 30 beaches, and Share turns one into a code (it starts with MOB1.) that a friend can paste in to play the same beach.