How it works
Three rules. That’s the whole game.
Drag one unbroken line from 1 to the last number.
Reach the numbers in order — no skipping ahead.
Fill every open cell. Drag back over the line to erase.
The climb
Six chapters. A hundred and fifty levels.
Every chapter takes the whole app with it. The board, the buttons and the line all shift to its colour, so a screenshot tells you how far in you are — and the last chapter is almost colourless on purpose.
First Light
Learn the line
Detour
Room to wander
Crossroads
Choose well
Bottleneck
Tight squeezes
Labyrinth
Walls everywhere
Singular
One way only
Two puzzles you can’t crack shouldn’t wall off a hundred you could. The next chapter opens after ten solves, not twenty-five — and a locked row always tells you exactly what it wants.
Level design
The last chapter has only one answer.
Every level is built from the answer outwards. A real route is found first, then the numbers are dropped onto it — so a level that cannot be solved is physically impossible to produce.
Difficulty is measured, not guessed. The solver counts every solution a board has, and that count is the difficulty. A 6×6 with forty ways through is a warm-up; one with three is an evening.
And the curve is a selection, not a sequence. Around four thousand candidates were generated and scored, then each chapter’s twenty-five were picked evenly across its band. Nothing was left in because it happened to come out of the generator.
Which leaves Singular: twenty-five boards, verified, where the line you find is the only line that works.
The same 150 levels ship on every device. No server, no daily shuffle, nothing generated behind your back — so level 3–24 is the same puzzle for you as for everyone else.
Feel
Designed around the drag.
- A crisp tick under your finger for every cell, and a firmer pulse the moment you reach a number.
- Drag back over the line to erase — or cut it at any earlier cell and carry on from there. There is no eraser mode to find.
- Undo takes back one step, and restart puts you back on the 1 — without quietly resetting your clock.
- A hint that rewinds to where your line was still right, then shows three more cells. It costs you the flawless badge, nothing else.
- The banner names the rule you broke — in order, or every cell — instead of just refusing to move.
- Every note is synthesised as you play: one step up a major pentatonic scale per cell, three octaves of it, and not a single audio file.
- It never interrupts your music or your podcast. The sound layer sits politely on top, or switches off entirely.
- VoiceOver plays the whole game, with four directional actions and a running count of what is filled and which number is next.
Free to start
Fifty free. €3.99 for the other hundred.
First Light and Detour — fifty puzzles — are free, with nothing withheld inside them.
One payment opens the remaining hundred and the four harder chapters. No subscription, no ads, and no upsell in the middle of a puzzle.
Every device
Your progress follows you.
Solved levels, best times and flawless badges sync through your own iCloud, so the iPad picks up where the iPhone left off.
If two devices solved the same level, the faster time wins and the badge survives. The unlock restores on all of them.
Ten languages
All of it translated.
Not just the menus — the rules, the banners and the small line of encouragement when a chapter opens.
Private by design
No accounts. No ads. No analytics.
Sikku collects nothing — no tracking, no advertising, no third-party SDKs, nothing to sign up for. Its privacy manifest declares no collected data at all.
Your progress is yours: on your device, and in your iCloud.
More from us
Same promise, different puzzle.
Support
Questions? Ideas? A level that feels wrong?
Sikku is made by one person who reads every email. Bug reports, feature requests, or a board you think is unfair:
dresende@thinkdigital.pt