Tide Defense: reading the 40-second tide clock, which of the 11 towers hit what, and how the three stars are counted

Tide Defense is a tower defense on a coastline. Enemies follow a fixed route to your lighthouse, and you spend scrap to build towers along it. What makes it different is the tide: the map never changes during a stage, but the rules for building and moving do. You can play it in your browser.

The tide clock

One full cycle takes 40 seconds, split into four phases of 10 seconds each: Low tide, Rising, High tide and Falling. Every stage starts at Low tide. On the first stage, Quiet Cove, the clock runs about a third slower so you have time to learn it.

Where you can build

• Sand and rock: any tower, at any time.
• Mid-shore (the shallow band that floods): only at Low tide or Falling. Rising and High tide block new builds there.
• Deep water: only the Buoy Beacon, which floats.
• The lighthouse tiles: nothing.

How the tide changes enemy speed

• Boats and other water units (Skiff, Drift Raft, Jelly Drift, Tide Ray, Cutter and the Boss Skiff) move at half speed during Low tide and Falling.
• Walkers such as crabs, seals and hermits are 25% slower at High tide.
• Flyers ignore the tide.

Towers: ground, air or both

Every tower can hit only ground units, only flyers, or both, and a Gull will fly straight past a Harpoon Pier. The tray shows only the towers your current stage allows; more unlock as you go deeper.

| Tower | Price | Hits | First stage | |---|---|---|---| | Harpoon Pier | 55 | Ground | Quiet Cove | | Net Casters (splash, slows) | 70 | Ground | Quiet Cove | | Buoy Beacon | 85 | Both | Quiet Cove | | Fog Horn (splash, stuns flyers) | 90 | Air | Quiet Cove | | Salt Mortar (splash, long range) | 105 | Ground | Coral Shelf | | Sand Drill (two hits per volley) | 65 | Ground | Storm Jetty | | Signal Flare (longest range) | 80 | Air | Storm Jetty | | Twin Trident (pierces a second enemy) | 95 | Both | Wreck Harbor | | Sky Snare (splash, slows) | 100 | Air | Wreck Harbor | | Powder Keg (big splash) | 120 | Ground | Beacon Atoll | | Spark Coil (chains to two more enemies) | 110 | Both | Beacon Atoll |

Towers go up to level 3. Each level adds 35% damage, a quarter of a tile of range and slightly faster fire. Level 2 costs 70% of the tower's price and level 3 costs 140%. Selling returns 55% of the price for each level the tower has.

Buoy Beacons and the High-tide window

At High tide a Buoy Beacon's own range grows by 35%, and every other tower within about 2.6 tiles of it gets 18% more range and fires about 12% faster. Since High tide is also when walkers slow down, a beacon placed between two strong ground towers turns those 10 seconds into your best damage window.

High tide also pays: once during each High tide, if the lighthouse still has at least 55% of its HP, you get a scrap bonus (the healthier the lighthouse, the bigger it is).

Stages that change the rules

• Fog (Wreck Harbor, Moonlit Pier): every tower's range is about 23% shorter. Build closer to the route.
• Two routes (Coral Shelf, Kelp Forest, Driftwood Bay): water units and bosses always take the second route, flyers alternate, and about one walker in three joins them. Defend both.
• Bosses: the last wave of Beacon Atoll, Driftwood Bay and Crystal Lagoon brings a Boss Skiff together with an escort of other enemies.

Enemies get tougher on every stage. A leak costs the lighthouse 12 HP for a walker or boat, 8 for a flyer and 28 for a boss.

Stars and unlocking

• Clearing a stage gives 1 star, 2 if the lighthouse ends with at least 55% HP, 3 at 85% or more.
• The third star has one more condition: you must not spend more than 2.5 times the scrap you earned during the stage (scrap from kills and tide bonuses; the starting scrap doesn't count). Building, selling and rebuilding again and again can drop you to two stars.
• Each stage needs as many stars from the earlier stages as its position minus one, so any clear opens the next stage.

On the online leaderboard your score is your total stars × 1,000, plus 10 per star in the run you just finished, plus the scrap you had left.

More on the Tide Defense page, or hold the lighthouse now.