Rubus

Rubus is a bite-sized logic puzzle that lives in your browser toolbar — no installation fuss, no accounts, no ads.

─── HOW TO PLAY ───

Every cell holds a value from 0 to 3. Tap a cell and it — along with its neighbours — counts down by one. Values wrap: 0 goes back to 3. Clear the entire grid to zero to win.

That's all the rules. The depth comes from figuring out which cells to tap, in what order, to unravel the puzzle without creating new problems elsewhere.

─── TWO MODES ───

Human mode — tapping a cell affects the cell plus its four orthogonal neighbours. Tight, local, surgical.

God mode — tapping a cell affects the entire row and column. Sweeping, interconnected, ruthless.

Both modes have independent progress, independent stats, and their own hint counters.

─── PROGRESSION ───

Start on a 5×5 grid at Level 1. Each grid size has 10 levels of increasing difficulty. Clear Level 10 and you unlock the next grid size. Progress carries forward — there's always a harder puzzle waiting.

─── HINTS ───

Stuck? The hint button highlights the single most impactful cell to tap next. Hints are finite — you earn 5 fresh hints each time you clear a level you haven't beaten before. Use them wisely.

─── NO NONSENSE ───

• No account required
• No internet connection required
• No ads, no trackers, no analytics
• Progress is saved automatically on your device
• Works completely offline

─── PERFECT FOR ───

A two-minute brain reset between tasks. Commuters. People who like maths. People who think they don't like maths but actually do.