Daily Slitherlink

What “Daily” means here

Daily Slitherlink is a specialist daily mode, not a new member of the platform's frozen Today’s 6 rotation. The calendar date is converted into a deterministic specification that chooses a supported grid size and difficulty. That specification then selects a verified source and symmetry through the same local deterministic engine used by Practice.

Because the date drives the choice, reopening the same date restores the same puzzle. There is no server queue deciding which board to send to a visitor and no account-specific randomization. Two browsers using the same build and date receive the same Daily specification, while each browser keeps its own local progress, completion history and streak.

The puzzle rules do not change in Daily mode

The objective is still one closed loop. Numbered cells require exactly that many surrounding line segments. Every dot touched by the loop must have two line segments, so the route cannot branch or end. All used segments must belong to one connected cycle, which prevents two smaller correct-looking loops from counting as a solution.

The same explicit Line, Cross and Erase tools are available. Cross marks remain optional notes, but they are saved because they often carry most of the reasoning in a difficult loop puzzle. Hint, Check, Undo, Redo, Restart and Share work the same way as Practice, so the Daily mode does not hide useful controls simply to create artificial pressure.

How the date-stable puzzle is chosen

The Daily selector uses a deterministic pseudorandom stream keyed by the date. It first chooses among the supported 5×5, 6×6 and 7×7 sizes and Easy, Medium and Hard difficulty pools. It then asks the frozen bank selector for a source and one of eight rotations/reflections. Calling the same selectors again with the same date must reproduce the same specification; that determinism is tested across a full 365-day fixture during release verification.

The date itself does not prove that a puzzle is solvable. Solvability comes from the frozen bank verification. Every source was already accepted only after an exact solver reported one solution, and the independent release verifier solves all eight symmetry variants again. Daily mode simply chooses among those preverified possibilities.

What gets saved

The browser stores your current line and cross states, move count, source identity, symmetry, Clean/Assisted flag and completion state under the Daily date key. If you close the tab halfway through and return later, the saved board is restored rather than replaced with a fresh puzzle. A completed date also restores as completed instead of creating another solve entry.

The specialist history records the date, size, difficulty, move count and whether the completion was Clean. Consecutive completed dates form the Slitherlink streak. That history is browser-local; there is no global leaderboard, percentile, fabricated rank or cross-device synchronization claim.

Clean and Assisted Daily solves stay distinct

A Hint reveals one verified edge state. Check analyzes contradictions. Undo, Redo and Restart let you explore earlier decisions. Those controls are useful, so they remain available, but using them changes the run to Assisted. This prevents a heavily guided completion from silently replacing a clean record while still allowing the Daily date to be completed and learned from.

Cross marks by themselves do not make a run Assisted. They are ordinary player-entered notes, equivalent to marking impossible edges on paper. A right-click cross on desktop and the Cross tool on touch devices both remain part of normal clean play.

How to approach a Daily board without guessing

Scan 0 clues first, then high-information 3 clues. Check dots around any lines you draw, because two lines at a dot immediately exclude all other incident edges. If a dot has one line and only one undecided exit, that exit must be part of the loop. These vertex deductions often unlock clue deductions several cells away.

When a numbered cell already has the required number of lines, cross its remaining undecided borders. When the number of undecided borders equals the number of lines still needed, all those borders are forced. Repeat this local cycle before considering more global connectivity.

As the board fills, watch for premature closure. If adding an edge would create a closed cycle while other required line segments remain outside it, that edge cannot be correct. Conversely, near the end, the single-loop requirement can force the only connection between two unfinished chains even when the surrounding number clues alone do not appear decisive.

Why Daily Slitherlink is separate from Today’s 6

The platform's existing Today’s 6 lineup is deliberately frozen for stability. New specialist games are added to Practice and may receive their own daily history, but they do not silently alter the established six-game schedule. Daily Slitherlink therefore offers a repeatable date-based habit without changing old scores, archive dates or expectations for people already using Today’s 6.

This separation is also useful for QA. The migration test verifies that opening Slitherlink on a populated V0.99 state creates the new V0.100 store while preserving the older serialized store and all existing specialist statistics. Completing Daily Slitherlink must update only the new Slitherlink specialist history; the general Today’s 6 days collection remains unchanged.

Practice mode is still available when the Daily is finished

Finishing the date does not lock the specialist for the rest of the day. Unlimited Practice remains available with explicit size and difficulty controls, so a Daily 5×5 can be followed by a harder 7×7 or by another medium board without changing the completed Daily record. Practice uses its own seeded autosave keys and does not increment the specialist Daily streak.

This distinction also prevents a common daily-game ambiguity: requesting Fresh Practice never replaces the board attached to the calendar date. The Daily key stays stable, while a fresh Practice request gets a new URL seed. Sharing or reopening that Practice URL therefore reproduces its own source and orientation independently of the date-based board.

If a Daily puzzle feels difficult, using Hint or Check is preferable to random guessing because the resulting Assisted status is explicit. The goal of the local record is to preserve what actually happened rather than punish the use of learning tools. A later clean Practice solve can still be tracked separately, and tomorrow's Daily starts from a new deterministic date specification.