A logic puzzle with a one-sentence rule that gets deeper the more you think about it. Tap a lantern and every lantern in its reach switches between dark and lit; the goal is to light them all. The catch: lighting one spot often darkens the one next to it.
There are 5 chapters and 30 levels, and each chapter adds one new idea: boards with gaps, "cross" lanterns that reach the diagonals, "three glows" where lanterns cycle dark → dim → bright, and "ring" lanterns that switch the eight around them but not themselves. The little dots on each lantern show exactly what it reaches.
Every puzzle is generated by the game and checked with Gaussian elimination (mod 2 / mod 3) to have exactly one solution, so each one can be solved by reasoning, never by luck. The "fewest moves" shown is the length of that unique solution. Every chapter also has endless random practice.
How to play
- Tap "Play", or pick a chapter and level from "Levels". The first time you open a new chapter, a small picture shows its new rule.
- Tap a lantern: it and the spots marked by the little dots on it switch together. Plus lanterns reach up, down, left and right; cross lanterns reach the four diagonals; ring lanterns reach the eight around them (but stay as they are).
- Light every lantern to clear the level. The top shows "moves / fewest moves", and finishing in the fewest moves earns a star.
- Stuck? "Undo" takes back one move and "Restart" resets the puzzle. "Hint" works out, from the board as it is now, which lantern to tap next and how many moves are still needed at least. Hints never cost you anything.
- Clearing 4 levels of a chapter opens the next chapter. Each chapter also has "Random practice" with fresh puzzles.
Controls
- Phone / tablet: tap a lantern. It counts when you lift your finger, so you can slide off to cancel a slip.
- Mouse: click a lantern. Hovering over one outlines in green every lantern it would switch.
- Keyboard: arrow keys (or WASD) move the cursor, Enter / Space taps; Z or Backspace undo, R restart, H hint, Esc menu, M mute. On the level screen, ← → change chapter and 1–6 pick a level.
For parents
- Made mainly for ages 13 and up, and 9–12-year-olds can ease in through Chapter 1. It is a take on the classic "Lights Out" puzzle, which is linear algebra in disguise (simultaneous equations mod 2 / mod 3). Players soon discover patterns such as "tapping twice is the same as not tapping" and "the order of taps does not matter", which builds systematic reasoning and planning.
- There is no timer, no losing and no lives; undo, restart and hints are always available. Every puzzle has exactly one solution, so no guessing is needed. Everything is warm lanterns and a night sky, with no violence, scary content or gambling.
- No chat, in-app purchases, ads, outbound links or online leaderboards, and no personal details are ever asked for. Cleared levels, best move counts and the mute setting are stored only in this device's browser, and the game also works offline.
