As of 1.0.17 (2026-10-15)
The game and installation
Q1. What kind of game is Coral Keeper?
It's a casual defense game where you build a deck of sea friends and protect the coral reef. You place crew, merge identical crew to raise their ★ level and hold off the waves of enemies, and collect real-crab Reef Keepers through eggs and Breeding. For details, see the game introduction.
Q2. Is it free?
Yes, installing is free. There are optional in-game purchases (Pearl top-ups, the Starter Pack, the Deep-Sea Pass Premium, crew-exclusive packs and more).
Q3. Where can I get it?
You can get it on ONE store (Android) and Apps in Toss (mini-apps inside the Toss app). The ONE store address is https://m.onestore.co.kr/v2/ko-kr/app/0001010212. There is no Google Play release information yet.
Q4. What devices does it run on?
It installs on Android 7.0 or higher. Apps in Toss runs on devices that have the Toss app installed. It is provided in Korean, and the ONE store version can be switched to English under Settings > "Language" (the Apps in Toss version is fixed to Korean).
Q5. Do I need to log in or sign up?
No. There is no login or server account, and we don't collect personal information such as your name or contact details. Your progress is saved on your device.
Q6. Can I play without internet?
In the ONE store version, the game files are inside the app, so battles and growth run on your device without a server. Features that talk to the store, such as purchases and rewarded ads, need internet.
Q7. What age is it for?
It is rated All ages (self-rated through the Game Rating and Administration Committee (GRAC), content descriptor: Violence). Cartoon-style sea creatures fight each other, with no blood or bodily mutilation, and there is no chat feature.
Purchases and ads
Q8. Can I clear it without spending money?
Yes. Stages, Hard, Special and the Arena are all designed so you can grow with free rewards (Shells · Pearls · crew cards). There are free daily chests, check-in, missions, the Farm and Sea Route rewards. By the developer's calculation, a free-to-play player who plays 30 minutes a day takes about 12 days to raise all 9 deck cards to Lv5 and about 4-5 months to reach Lv10 (an estimate). Paid items are an option that shortens this time.
Q9. What paid items are there?
There are 3 Pearl top-ups (100 · 550 · 1,200 Pearls), the Starter Pack (₩3,300, once), the Deep-Sea Pass Premium (₩9,900, once), Remove Ads (Apps in Toss version, once), 4 crew-exclusive packs (Sea Hare · Pistol Shrimp · Sea Otter · Sea Turtle), 2 Reef Keeper packs (Snow Crab · King Crab), and limited offers (the Depth Milestone offer, the Crew Growth Pack) and more. The price is the amount shown in the store's checkout window. Apps in Toss adds VAT, so the amount may differ slightly from ONE store.
Q10. What changes if I buy Remove Ads?
Remove Ads is a one-time item sold in the Apps in Toss version. Once you buy it, tapping a rewarded-ad button gives you the reward instantly without an ad. The daily limit (5 times) stays the same. Also, when a match ends, the "2× Shells" bonus is credited automatically when the result screen appears, and on the Farm you collect with a single "2× harvest" button. The only ads in this game are rewarded ads that you tap only when you want to watch, so ads are never forced on you.
Q11. Why doesn't the ONE store version have a Remove Ads item?
The ONE store version has had no ads from the start, so it is already in the same state as having bought Remove Ads. When you tap an ad reward it is granted instantly, and you can get it up to 5 times a day.
Q12. Where can I see the odds of chance-based items?
You can check them with the "Odds" button in the Shop and on each screen. The Reef Keeper egg grade table is published (Shell Egg: Common 75% · Rare 25% / Pearl Egg: Common 30% · Rare 45% · Heroic 22% · Legendary 3% / Golden Egg: Rare 35% · Heroic 55% · Legendary 10%), and the Breeding odds, color variant odds and level effect odds (Lv5 10% · Lv8 25% · Lv9 50% · Lv10 80%) can also be viewed in the game.
Q13. Can I get a refund?
Payments and refunds follow each store's policy. For ONE store it is the ONE store customer center, and for Apps in Toss it is the Toss customer center policy. For the refund criteria for unused items, check each store's guidance.
Q14. Can I get paid crew for free?
The Sea Otter can also be collected for free. 1 ad = 1 card (2 times a day), 25% of Arena win cards are Sea Otter cards, and with 30 cards + 3,600 Shells it joins you (about 9-10 days). The Sea Hare, Pistol Shrimp and Sea Turtle can for now only be obtained through their exclusive packs. Reef Keepers (Snow Crab, King Crab and others) can be obtained for free through eggs, Breeding and stage-boss joins. For details, see the Crew Codex.
Progress and saving
Q15. Where is my progress saved?
It is saved on your device. The Apps in Toss version also records it in Toss storage, and when you reopen the app, it restores whichever is newer.
Q16. Can I continue if I change devices?
In the Apps in Toss version, with the same Toss account it restores from Toss storage. In the ONE store version, copy your backup code under Settings > "Data backup," then paste it into "Restore" in the same menu on your new device. The backup code contains your entire progress, so don't show it to anyone.
Q17. What about my purchases if I delete the app and reinstall?
Permanent items (the Starter Pack, Pass Premium and so on) are built to be restored from the store's purchase record. Even if the app closes right after a payment, the delivery is recovered the next time you launch it. This doesn't apply to consumable items such as Pearls. However, deleting the app erases the progress saved on your device, so back it up first.
Q18. Can I get past the daily limits by changing the time?
If you set the device clock back, the daily reset and Farm harvest are blocked.
How to play
Q19. What are the merge rules?
Only identical crew with the same ★ level merge (★1 + ★1 = ★2, ★2 + ★2 = ★3, up to ★3). Dragging onto a crew member you can't merge with swaps their places. Buying a card and placing it right onto the same crew member also merges them. ★2 has about 2.3× attack and ★3 about 5.8×.
Q20. Cards aren't appearing, or only the same crew keep appearing.
Cards come from only the crew in your deck. If a deck slot is empty, fewer cards of that Cost appear. Fill 3 each of 3-Cost, 5-Cost and 8-Cost in the Codex. 8-Cost cards don't appear on turn 1, and their chance rises as turns go on.
Q21. It says "not enough Power" and I can't enter.
Each stage has an entry Power (starting from 1,180 for Stage 2 Step 1). Power rises with the levels of the 9 cards in your deck, so level up your crew in the Codex. An 8-Cost crew member raises Power more for the same level-up.
Q22. I got a new crew member but it isn't in my deck.
New crew are automatically placed in a deck with an empty slot for that Cost. If your deck is already full, you need to swap them in yourself. The base and variant (II) forms of the same crew member can only be put in one deck as one of the two.
Q23. What's the difference between Shells, Pearls and crew cards?
Shells are the basic currency, used for level-ups and buying eggs. Pearls are the more precious currency, used for Chests, Epic bundles, Breeding eggs and more. Crew cards are level-up materials, and are collected separately for each crew member.
Q24. What happens if I quit?
If you quit, you only receive Shells and Pass XP for the turns you survived, and get no participation rewards such as crew cards, Sea Route trophies or match counts. It also doesn't count toward the "battle count" of Daily and Weekly Missions.
Q25. Is the Arena real-time?
No. Arena opponents are AI rivals, not people, and it is not a real-time match where you connect and play against an opponent right away. You face 12 sea rivals and League-specific AI, and an in-game notice also says "For now, you can practice in the NPC League." Real-time Arena server integration is only announced as planned.
Q26. What are Arena tickets?
1 Arena match costs 1 ticket (Defender battles are free). They refill automatically at 1 ticket every 30 minutes up to 6, and you can refill 2 by watching an ad or 5 with 30 Pearls (up to 5 times a day).
Q27. How do I get Reef Keepers?
Buy a Shell Egg, Pearl Egg or Golden Egg and hatch it in a nest, breed a ♂♀ of the same species, or fill 9 stars in a stage to have its boss Reef Keeper join you. Your first Shell Egg is free once, after you clear Stage 1. You have 3 nest slots by default, and unlocking the Deep-Sea Pass Premium adds 3.
Q28. How often do color variants appear?
The base odds are Normal 93% · Blue 3% · Golden 2% · Albino 1% · Split 0.7% · Ghost 0.3%, and rare variants appear more often depending on the egg type. Blue, Golden and Albino are inherited through Breeding.
Q29. When does Hard difficulty unlock?
It unlocks when you open the Reef Sea Route trophy 213 slot and clear that stage on Normal difficulty. Shells and trophies are doubled, and you get 30 Pearls on the first clear.
Q30. How much can I get per day?
You can get up to 60 Pearls a day from battles, and Shells in full for up to 20 matches a day and 30% after that. Tide Pool and Boss Rush are 3 runs each, Arena win rewards go up to 5 wins, and rewarded ads go up to 5 times.
Other
Q31. Where do I report an error or get in touch?
Contact us by email at contact@zackson.kr (the official address listed on the Google Play version's Settings screen and in the privacy policy). For the ONE store version, you can also contact the seller through the contact info on the ONE store product page. It's faster if you include the symptoms, your device model and the game version ("Coral Keeper vX.X.X" at the very bottom of the Settings screen).
Q32. The screen stutters or the sound crackles.
Try turning on "Reduce effects (low-end devices)" in Settings. If you still have problems, let us know at the contact address. It's also a good idea to update the app to the latest version (in the ONE store version, an update notice window appears when a new version is available).
Q33. How do I use a coupon?
Enter the code under Menu > "Coupon," and each can be used only once. Coupon codes are announced through official event notices.
Q34. Is there an official community?
Check official information and notices on the Coral Keeper page of this site (https://zackson.kr/l/coral-keeper). If you log in, you can leave your thoughts as comments on the same page. Send inquiries to contact@zackson.kr.
Q35. Are there Toss Points missions?
The Apps in Toss version had Toss Points missions (finish the tutorial: 2 points · 1 match a day: 2 points · play 10 matches: 30 points · 1 Hard match: 30 points; the match must be played to the end, and quit matches don't count). They may end without advance notice once the budget runs out.