The Complete Feature Guide

Welcome to Chess Online! Beyond playing against the computer, the app has many exciting features for playing with friends and the community. This article introduces each feature in detail.

♞ Play vs the Computer — 10 Levels from Easy to Extremely Hard

The most basic mode: you play against the computer with 10 levels of increasing difficulty.

• Levels 1–3: for beginners — the computer plays quite "gently", ideal for learning the rules.
• Levels 4–6: the computer starts thinking tactically — suitable for intermediate players.
• Levels 7–8: a real challenge — the computer looks many moves ahead.
• Levels 9–10: extremely hard — for masters who want to test their skill.

After every game, you earn experience points (XP) and rating points (Elo). Beating a higher-level computer earns more points.

👥 Game Rooms — Play Live Against Real People

Game Rooms are where you create private rooms to play against friends in realtime — every move you make, your opponent sees it instantly.

How to Create and Join a Room

Open 👥 Game Rooms.

Press Create Room — you'll receive a room code.

Send the room code (or the invite link ?room=CODE) to your friends.

Friends enter the room code to join.

There are 2 types of rooms:

• Private rooms: only people with the code can enter.
• 🌐 Public lobby: public rooms — anyone can watch and join.

What's Inside a Room?

• Automatic turn queue: the first 2 people on the list play each other; the winner/loser moves to the back of the queue.
• Side switching: each new game automatically swaps colors (if you played White last game, you play Black next).
• Move-by-move comments: a great move can be annotated with a comment 💬.
• Flying emoji reactions: drop 😂👏😮 right on the board.
• Round-robin tournaments: the host can organize tournaments, with the system calculating the standings automatically.

Guests Can Watch

You don't need to sign in to enter the public lobby and watch ongoing games. To join in playing or commenting, just sign in for free.

⚔️ Challenges — Challenge a Friend to a Game

Want to play a game right away against a specific friend? Use the Challenge feature:

Go to 👤 Friends (sign-in required).

Add friends by searching for their username.

Press Challenge next to a friend's name.

Your friend will receive a push notification "⚔️ Challenge!" — tapping it opens the challenge directly to Accept or Decline.

When accepted, both of you automatically enter a shared game room.

✉️ Correspondence Chess — Play Without Being Online Together

Friends aren't always free at the same time as you. Correspondence chess solves this:

• Each person plays one move whenever they're free, with no time limit on thinking.
• When your opponent moves, you get a push notification "✉️ Correspondence — your move!".
• When the game ends (checkmate or resignation), both of you receive the result notification.
• Tapping a notification opens that game directly.

It's a great way to play many games at once against different friends, a few moves each day.

🧩 Puzzles — Train Your Tactical Thinking

Daily Puzzle

One puzzle a day: checkmate in 1 move. Solve it correctly to keep your day streak — solving on consecutive days earns big XP rewards.

Community Puzzles

Players can create their own puzzle positions and challenge everyone to solve them. Puzzles with many ❤️ make it to the selection, with the author earning XP rewards and a name credit.

🏆 Leaderboard, XP and Titles

Every win or loss affects your Elo rating. Beating a stronger opponent earns more points than beating a weaker one.

You earn XP from all activities: playing games, solving puzzles, checking in, commenting, inviting friends... Enough XP levels you up and earns you titles.

The 🏆 Leaderboard shows the top strongest players — where do you stand?

🎁 Daily Check-in and Quests

• Check-in: claim XP rewards each day; consecutive check-ins earn bonus rewards.
• Starter quests: simple quests for newcomers — each quest earns XP rewards.
• Refer friends: invite friends through your personal link — both of you earn XP when they play their first game.

🔔 Notifications — Never Miss Your Move

Turn on push notifications in Settings to receive alerts even when the app is closed:

• ⚔️ Someone challenged you.
• ♟️ It's your move in a room.
• ✉️ It's your move in correspondence chess.
• 🏆 Your opponent resigned / the correspondence game ended.

Note for iPhone users: push notifications require iOS 16.4 or later, and you must install the app to your home screen (open it in Safari → Share → Add to Home Screen), then open the app from the installed icon.

📊 And There's More...

• 📜 History: review every game you've played, analyzing each move.
• 📤 Share: create beautiful result images to share on social media.
• 🌐 Vietnamese / English: customize in Settings.

---

Have fun! If you have suggestions or spot a bug, don't hesitate to contact us. ♞