Svetilnik
Slovenian for lighthouse. A board of white squares and scattered walls, dark to begin with. Place lamps until every white square is lit — and the rules that make it a puzzle rather than a chore are only three lines long.
A lamp throws light along its row and its column until a wall stops it, which means a single well-placed lamp can reach across the whole board and a badly placed one lights almost nothing. Each board has exactly one arrangement that satisfies everything, and it is always reachable by reasoning — there is never a point where the only way forward is a guess.
- Light everything. Every white square must end up lit, by some lamp, along a clear row or column.
- No lamp may see another. Two lamps in the same unbroken row or column are a conflict, always.
- Numbered walls count. A wall carrying a number touches exactly that many lamps on its four sides — no more, no fewer.
- Live feedback. Lit cells brighten as you go, and a conflict or an exceeded number is flagged gently rather than hidden until the end.
- Room to think. Tap to place a lamp, tap again to mark a square you have ruled out; undo lets you explore, and a rationed hint reveals one lamp that is already forced.
com.lucka.svetilnikAn empty grid is not a puzzle
Take all the walls away and the thing becomes solvable by anybody, in far too many ways. The exact number is the nicest small result in this game.
With no walls, light runs the full length of every row and column, so two lamps conflict exactly when they share a row or a column — which makes lamps into rooks on a chessboard. Non-attacking rooks sit in distinct rows and distinct columns, and a set of them lights every square only when there is one in every row. So the valid arrangements on an empty n × n board are precisely the permutations of n: there are n! of them, every one of them correct.
Answers, before and after the walls
How far one lamp reaches, by wall count
Not here: no board, no walls, no numbers, no lamp placed and nothing solved. No technique, no deduction order, no hint about where a forced lamp hides. This counts what the rules allow before a puzzle has been built. Building one is the craft, and solving it is the game.
We do not sell electricity
Energija is the Slovenian word for energy, and with a lightning bolt in the mark the misunderstanding is an easy one to have. AK energija d.o.o. is a software company. It does not supply, trade, meter or bill electricity, gas, heat or any other form of energy; it is not a supplier, an aggregator or an installer, and it has no connection to any energy utility. If you arrived here looking for a power contract, this is the wrong door, and we would rather say so on the front page than let you find out three clicks in.
A mailbox, read by a person
Bugs, a chart that behaves oddly, a question about what the app keeps: zarek@glnsistem.space. Everything Svetilnik stores on your phone, and everything it does not, is written out on the Privacy Policy page.