Why fog of war makes Sudoku better
I’ve been playing Sudoku for years. At some point I noticed I was solving puzzles mechanically — scanning, applying techniques, filling cells. Still enjoyable. But after years of it, I realized what I actually missed wasn’t harder logic — it was the feeling of finding something.
Standard Sudoku hands you all the information the puzzle will ever give you before you’ve done anything. The whole board is there. The challenge is pure deduction, and deduction is fine. It’s just a different thing from discovery.
Hiding the board
In Sudoku Fog, most cells start obscured. You see the starter clues and not much else. Each number you correctly place reveals the cells around it — one placement at a time.
The rules don’t change. Every row, column, and 3×3 box still needs 1–9 without repeats. I originally thought the fog was just hiding information. It ended up changing how I approached every puzzle.
The most obvious shift: placements feel like rewards. You fill a cell, the board shows you something new, you have more to work with. When the loop is running, there’s a momentum that standard Sudoku doesn’t have. Stuck in standard Sudoku means “I can see everything and can’t figure it out.” Stuck in fog Sudoku might just mean “I haven’t uncovered that region yet.” Those are genuinely different feelings.
The time I tried to add X-Wings
Early on, I wanted fog Sudoku to support the full range of Sudoku difficulty — including advanced techniques like X-Wings and Swordfish. They’re advanced techniques that rely on seeing almost the entire board at once. In standard Sudoku they produce some of the most elegant solving moments.
That’s where things fell apart. The solver works on what’s visible. With most of the board under fog, it simply couldn’t find the patterns — the cells it needed to see were hidden. I tried adjusting the generator to place clues more strategically, but to make X-Wings findable, I’d have to reveal so much of the grid that the fog became meaningless. Or I could leave the fog in place and accept that the solver just gets stuck.
Eventually I stopped trying to fix it. The moment I realized this wasn’t while redesigning the generator — it was during playtesting. I kept waiting for an X-Wing opportunity that never came, and at some point understood: the fog itself was the reason. Once I accepted that, I stopped treating it as a bug. It’s just what this mechanic is good at — and what it isn’t.
Whether that’s a problem depends on the player. Someone who finds advanced techniques more exhausting than satisfying probably won’t miss them. A competitive solver looking for a genuine challenge will hit that ceiling eventually. I don’t know yet which of those shows up in larger numbers.
One thing that worked unexpectedly
Hidden cells sometimes contain dishes — collectibles from a global cuisine collection. You don’t know what’s there until the fog lifts.
I expected this to be a light secondary reward. What I didn’t anticipate was how much it changed the feeling of each reveal. Completing a puzzle already requires uncovering every cell — that’s the goal. But with dishes hidden in the fog, each placement carries a second question alongside the logic: is there something here? It started as a tiny feature. It ended up changing how every reveal feels.
Try it
The app is finished and heading to Google Play. While it goes through the release process, there’s a free web demo — a few puzzles, no account required, works on any device.
The best way to understand what fog actually feels like is to play it for five minutes, not read about it. The reveal moment either lands or it doesn’t, and no amount of description substitutes for the first time it happens to you.
If you want to follow along before the full release, the DevLog is where I write about what was built, what broke, and what changed along the way.