When you first land on Sudokum.Net, the grid is waiting for you — along with a few other things: modes at the top, the Game Coach panel on the right, a score counter, a timer. You can solve puzzles without knowing what any of it does, but you'd be skipping over most of what the platform has to offer.
For first-time users: which mode unlocks when, how Game Coach works, how to pick up speed with the keyboard, how the leaderboard system operates — it's all covered below.
What Are You Looking At?
The Sudokum.Net interface is intentionally minimal. At the center is a 9×9 grid, at the top a timer and score counter, and on the right the Game Coach panel. In the upper left are the mode options: Daily Sudoku, Competitive Mode, Leaderboard.
Grid interactions are handled automatically: the row, column, and 3×3 box of the selected cell are highlighted. Cells containing the same number are color-coded — a feature that speeds up both finding naked singles and catching errors. In the upper right is a theme toggle: dark mode can be switched on to reduce eye strain during nighttime sessions.
Four Modes, Four Different Experiences
| Feature | Standard | Daily | Competitive | |
|---|---|---|---|---|
| Unlimited puzzles | ✓ | --- | ✓ | ✓ |
| Global leaderboard | --- | ✓ | ✓ | --- |
| Game Coach | ✓ | ✓ | --- | --- |
| Hints | Unlimited | Limited | Limited | --- |
| Score system | ✓ | ✓ | --- | --- |
| Streak tracking | --- | ✓ | --- | --- |
Unlimited puzzles in easy, medium, or hard. Time, error count, and score are all tracked. Game Coach is on and hints are unlimited. It's the ideal environment for learning, practicing, and developing specific techniques.
Score system: an easy puzzle is worth 25 points, medium 50, hard 100. Each mistake costs 1 point, and each hint proportionally reduces your score. Your score never drops below 0.
Everyone in the world solves the same grid — whether they play in the morning or at night. This shared starting point is what makes the global leaderboard meaningful: the same puzzle, different solve times, a genuine comparison.
Hints are limited in daily mode. Game Coach is available, but no extra hints are given once your quota runs out. Streak: your streak counter increases each day you complete the puzzle, and resets if you miss a day.
Game Coach and the number panel assistance are disabled — without any aids, raw time performance takes center stage. The competitive mode leaderboard is kept separate from the daily mode table, and is tracked both globally and by country.
Error management is critical: each mistake affects both your time and your ranking. Solving quickly but sloppily almost always results in a worse ranking than solving slowly but cleanly.
You can download and print puzzles prepared by difficulty level as PDFs. If you're dealing with screen fatigue, traveling, or want to give your kids a paper puzzle to work on, the Printable puzzle page is ready to use.
Game Coach: From Silent Guide to Teacher
Game Coach is Sudokum.Net's most distinctive feature. It's always active in the right panel — analyzing the current state of the grid and providing real-time feedback. It has three modes:
Silent
Game Coach is visible on screen but doesn't provide active feedback. It shows your completion percentage and the candidate list for the selected cell. Designed for those who want to track progress without needing ongoing analysis.
Balanced
The default mode. It analyzes the state of the selected cell — giving you information like "2 candidates remain in this cell: 4 and 7." It offers hints about which technique might apply, but never tells you the answer. It supports learning without creating dependency.
Teaching
The most detailed mode. It doesn't just describe the situation — it walks you through the applicable technique step by step. Is there a naked pair? Game Coach spots it and explains exactly how to use it. Built for beginners and anyone trying to internalize a specific technique.
Keyboard Shortcuts
Playing with the mouse works fine, but solving with the keyboard is both faster and more comfortable. Learn the shortcuts once and they become automatic:
| Key | Function |
|---|---|
| ↑ ↓ ← → | Navigate between cells |
| 1 – 9 | Enter a number in the selected cell |
| N | Toggle note mode — when active, numbers are saved as candidate notes |
| H | Hint — fills the selected cell with the correct number (affects score) |
| 0 / Del | Clear the number or notes in the selected cell |
| Backspace | Undo the last move — can be applied multiple times |
N mode is especially indispensable at medium and hard difficulty. Press N to activate it — the numbers you enter are then saved as small candidate notes rather than being placed as large digits. Press it again to turn it off. Backspace can be pressed multiple times; if you're not sure when you made a mistake, stepping back a few moves is usually the fastest fix.
The Leaderboard System
The leaderboard screen shows four separate tables: Competitive Mode, Daily Sudoku, Daily Sudoku Streak, and Score. Each table can be viewed both globally and by country. The top 10 players are shown in detail: time, error count, and username. Players outside the top 10 can see their own time and their rank for that day.
Score Table
Every puzzle earns points, and standard mode offers unlimited practice. A tangible way to see your progress.
Daily Streak
Your streak count is both a personal record and a global reference point. A great motivator for regular players.
Competitive Table
Game Coach off, no assistance tools. This is the only table that shows your true solving speed.
No Account Needed
All you need to appear on the leaderboard is a username at the start of a game. Using the same name consistently makes it easy to track your personal progress.
Where Should You Start?
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1
Standard mode, Easy difficulty. Set Game Coach to Teaching mode. For the first 5–10 puzzles, take the time to read through the instructional feedback.
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2
Learn the keyboard shortcuts. Use the arrow keys and N mode from your very first puzzle. Playing with the mouse is fine, but once you get used to the keyboard you won't want to go back — the speed difference in note-taking becomes especially noticeable from medium difficulty onward.
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3
Add the daily puzzle to your routine. Once you're comfortable in standard mode, make the switch to the daily puzzle. You'll quickly discover how it feels when your first streak breaks.
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4
Move to medium difficulty and switch Game Coach to Balanced. Once Teaching mode has done its job, switch to Balanced. Game Coach is still there, but now it's confirming rather than guiding.
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5
Try competitive mode. If you're holding steady at medium difficulty, turn Game Coach off and step into competitive mode. The leaderboard is waiting — and seeing it for the first time is more motivating than you'd expect.
Frequently Asked Questions
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No. Entering a username is all you need to join the leaderboard. Standard mode, daily mode, and competitive mode all work fully without an account. There is no account system at the moment — your username is tied to your device.
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In standard mode and daily mode, Game Coach does not affect your score — it only provides guidance. In competitive mode, Game Coach is disabled entirely; that mode's leaderboard measures unassisted solving speed.
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Each hint you use proportionally reduces the points you earn from that puzzle. Using hints while you're learning is perfectly fine — but if you're tracking your score, save hints as a last resort.
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Completing at least one daily puzzle each day is all it takes. The daily puzzle resets at midnight, so completing it at any point during the day is enough to maintain your streak.
Start with the daily puzzle, build your streak. Our strategy guide is always here whenever you're ready to sharpen your technique.