Game Modes — Coral Keeper

As of 1.0.17 (2026-10-15)

Coral Keeper has Stages (single-player), Hard, 3 Special modes (Tide Pool · Boss Rush · Endless Abyss) and the Arena (AI) League. Reward limits are per day (they reset when the date changes).

At a glance

Mode	Unlocks	One match	Daily limit	Main rewards
Stages	From the start	6 · 8 · 10 turns	No entry limit	Shells · Pearls · stars · Sea Route trophies
Hard	Sea Route trophies 213 + Normal clear	6 turns (more Elites and mini-bosses)	No entry limit	2× the Normal rewards, 30 Pearls on first clear
Tide Pool	Sea Route trophies 858	5 turns	3 runs	Up to 10 crew cards
Boss Rush	Sea Route trophies 248	5 boss fights in a row	3 runs	4 Pearls per boss
Endless Abyss	Sea Route trophies 623	Endless	No entry limit	Turn record, depth milestone rewards
Arena	From the start	Up to 9 rounds	Tickets required (up to 6), rewards for 5 wins a day	Rating, Pearls, crew cards, Egg Shards

1. Stages (single-player)

10 stages, each with 3 steps (1-1 · 1-2 · 1-3). Clearing all 3 steps unlocks the next stage.
As the step goes up, enemy HP goes ×1 → ×1.12 → ×1.25 and rewards go ×1 → ×1.2 → ×1.45, and a match goes 6 turns → 8 turns → 10 turns. A mini-boss appears on the middle turn and a boss on the last turn.
Steps 2 and 3 get a unique rule that differs by stage, and Elites appear from Step 2 (1 per turn in Step 2, 2 in Step 3).
You need enough Power to enter. Power is the total of the levels of the 9 cards in your deck, and Steps 2 and 3 require 1.1× and 1.2× the Step 1 requirement.

Stage	Name	Step 1 entry Power	Step 2 rule	Step 3 rule	Star challenge (third star)
1	Shallow Sandbar	0	Supply Current	Rapids	Keep 90% or more Coral HP
2	Coral Reef	1,180	Swarm	Regen Current	1 or fewer enemies reach the coral
3	Kelp Forest	1,700	Rapids	Night Sea	Defeat the boss within 18 seconds
4	Deep-Sea Cliff	2,400	Hard Shell	Supply Current	Clear with 7 or fewer crew
5	Hydrothermal Vent	3,000	Night Sea	Swarm	6 or fewer enemies reach the coral
6	Deep Sandbar	3,400	Regen Current	Cold Current	Clear without 8-Cost crew
7	Dense Coral Reef	3,700	Cold Current	Hard Shell	Defeat the boss within 17 seconds
8	Deep Kelp Forest	3,900	Rapids	Cold Current	Clear with 7 or fewer crew
9	Broken Deep-Sea Cliff	4,050	Regen Current	Hard Shell	3 or fewer enemies reach the coral
10	Deep Hydrothermal Vent	4,100	Swarm	Supply Current	Defeat the boss within 14 seconds

Unique rules: Rapids (enemy speed +20%), Hard Shell (enemy defense +15%p), Swarm (enemy count +40%, each enemy's HP −25%), Night Sea (enemies at the top look dim, Coral HP +20), Regen Current (enemies recover 0.6% HP per second), Supply Current (Bubbles +3 at turn start, enemy HP +10%), Cold Current (enemy speed −20%, enemy HP +25%).

Stars and star rewards

You can earn up to 3 stars per step: 1 for clearing + 1 for keeping 50% or more Coral HP + 1 for the stage's own challenge. In Hard, keeping 90% or more Coral HP earns all 3 stars.
There are 90 stars in Normal (10 stages × 3 steps × 3 stars) + 30 in Hard = up to 120 stars, and reward chests open based on how many you collect (3 stars: 20 Pearls + 300 Shells, 9 stars: 30 Pearls + 15 cards, 18 stars, 30 stars, 45 stars ... 120 stars: 500 Pearls + 20,000 Shells).
The first time you fill all 9 stars of a stage, that stage's boss Reef Keeper joins you (30-50% Potential).

Stage bosses

Each stage has a set enemy Reef Keeper: 1 Asian Paddle Crab · 2 Boxer Crab · 3 Horsehair Crab · 4 Snow Crab · 5 Red Snow Crab · 6 Swimming Crab · 7 Knobby King Crab · 8 King Crab · 9 Japanese Spider Crab · 10 Yeti Crab (if your Lead Reef Keeper is the same species, a different species appears). The boss name is shown in the form "the stage name's species name" (for example, the Asian Paddle Crab of the Shallow Sandbar). There are 5 mini-bosses: King Starfish, Shield Conch, Thief Cuttlefish, Healer Sea Cucumber and Numbing Electric Ray, and new species join in as stages get deeper.

Tide Gifts

Once you unlock the 141 Sea Route trophy slot, at the start of turns 4 and 7 you pick 1 of 3 gifts and keep its effect until the end of that match: Bubble Spring (Bubbles +10) · Wave Hop (3 free refreshes) · Coral Power (ATK +15%) · Fast Tide (ATK speed +12%) · Sturdy Coral (Coral HP +40) · Boiling Rage (Rage gauge +60%) · Weak Spot Insight (weakness damage ×1.8) · Reinforcements (summons a random 3-Cost ★2 crew member).

2. Hard

Fight the stages you've already cleared again with stronger enemies. Enemy HP rises a lot and they move 15% faster.
Shells and trophies are doubled, and stars are collected separately from Normal. 30 Pearls on the first clear of each stage.
The entry Power is about 1.6× the Normal entry line (Stage 1 adds +900), capped at a level that does not exceed a max-level deck's Power.
A match is 6 turns, with 2 Elites every turn and mini-bosses on turns 2 and 4.

3. Special modes (Special tab)

Tide Pool

A short 5-turn battle, 3 times a day.
You get crew cards for the number of turns you survive (2 cards per turn, up to 10 if you clear it). If you quit right after starting, you get 0.
Win for 5 trophies, lose for 1.

Boss Rush

3 times a day, you fight 5 wandering Reef Keeper bosses in a row.
4 Pearls and 3 trophies for each boss you defeat.

Endless Abyss

Keep descending and record how many turns you survive. The depth zone (background) changes every 10 turns, and enemy HP grows 16% with each turn.
10 Shells per turn, 2 Pearls every 5 turns, and 10 Pearls when you set a new best record.
Depth milestones (claimed only once): Turn 10: 20 Pearls + 10 cards / Turn 15: 40 Pearls + 15 cards / Turn 20: 60 Pearls + 20 cards / Turn 25: 90 Pearls + 30 cards / Turn 30: 150 Pearls + 50 cards.

4. Arena (formation battles against AI rivals)

Your Arena opponents are AI, not people. You face 12 named sea rivals (Tiny Bubble, Chilbok, Sand Pellets, Smiley Thief, Big Hand, Old Mitten, The Decorator, White-Belly Snow Crab, Wave Rider, Coconut King, Old Spider, Red King) and League-specific AI. The rivals have 4 personalities: Rusher, Defender, Merger and Boss Hunter. It is not a real-time online match, and an in-game notice also says "For now, you can practice in the NPC League."
How it works: your crew go out and fight the opponent's crew directly. When one side's crew are wiped out, the surviving side attacks the other's Reef Keeper, and Reef Keeper HP carries over between rounds. If there is no winner after 9 rounds, the result is decided by remaining HP percentage. Placement time is 20 seconds.
You pick the deck to use in the Arena from your 3 saved decks in the Arena tab (each deck has its own Reef Keeper), and the Reef Keeper's Rage skill uses Arena-specific values.
Tickets: 1 Arena match costs 1 ticket (Defender battles are free). Tickets refill naturally up to 6, with 1 ticket every 30 minutes. Watching an ad refills 2, and 30 Pearls refills 5 (up to 5 times a day).
Rating and League: +25 for a win, −15 for a loss (your first demotion each season is protected once). There are 5 League tiers.

League	Rating needed	Season reward
Sand	0	10 Pearls + 500 Shells
Reef	1,100	25 Pearls + 10 cards
Coral	1,250	45 Pearls + 15 cards + Giant Clam
Deep Sea	1,450	80 Pearls + 25 cards + Giant Clam
Legendary	1,700	150 Pearls + 40 cards + 3,000 Shells + Giant Clam

Seasons change every week, and you only get the season reward if you played 5 or more Arena matches that season. At the start of a new season, your rating is reset to half (relative to a base of 1000).
Win rewards: up to 5 wins a day give 3 Pearls + 1 crew card (with a low chance of a card for a crew member you don't have yet) and 1 Egg Shard of the opponent Reef Keeper's species (10 shards = 1 Egg). Even past 5 wins, your rating and trophies still count. A win gives 8 trophies and a loss gives 2.
Rival badges: you earn a badge the first time you beat each of the 12 rivals, and collecting all of them gives 30 Pearls. After 3 losses in a row, your next opponent switches to a practice opponent one step easier. Win streaks of 3, 5 and 10 earn win-streak titles (Riding the Current · Raging Current · Master of the Tide).

5. Other content

Content	Description
Farm (Sea Route 20)	Shells pile up even when you're away. You collect up to 8 hours' worth at once, and 1 crew card also piles up every 2 hours.
Breeding Lab (Sea Route 95)	Make eggs from a ♂ and a ♀ Reef Keeper of the same species. It costs 300-1,500 Shells depending on the species grade. Carapace width, color variants and Rage skills are passed on. You have 3 nest slots by default, and 6 when you unlock the Premium Pass.
Deep-Sea Pass (Sea Route 186)	Earn XP the more you battle to claim rewards across 100 levels. Unlocking Premium (₩9,900, once) makes the rewards bigger and adds 3 nest slots.
Daily Missions	Play 5 battles · defeat 600 enemies · merge 60 times · buy 6 Epic crew · defeat 4 bosses + ad (bonus) reward. Finish them all for a Chest (15 Pearls + 10 cards). Quit matches don't count toward battle counts.
Weekly Missions (clear Stage 2 Step 3)	6 new goals every Monday. Play 25 battles · 5 new stars · 20 bosses · 300 merges · Endless Abyss turn 15 · 1 Breeding.
Feats (Sea Route 1,128)	22 lifetime-record levels, with Pearl rewards at each level.
Daily check-in	A 7-day cycle of rewards.
Coupon	Enter a code under "Coupon" in the Menu (once per person).
Codex	28 crew types · 24 Reef Keepers · a record of the bosses you've met. You can also see enemies and rules in the Encyclopedia.

Daily limits at a glance

Item	Limit
Pearls from battles	60 per day (one-time rewards such as stars, first clears of a step, first Hard clears and Abyss records are excluded)
Shells	100% for up to 20 matches a day, then 30%
Tide Pool	3 runs
Boss Rush	3 runs
Arena win rewards	5 wins
Rewarded ads	5 times
Arena ticket refills (Pearls)	5 times