LOGIC · WORDS · PLACES PLAY IN YOUR BROWSERPlace bulbs to light every open square without letting two bulbs shine on each other.
Turn every pipe into one connected network.
1/16 connected · 16 open ends
No timer or lives. Switching puzzles starts a fresh board. Progress lasts while this puzzle stays open; it is not added to your account score. Daily puzzles change at 00:00 UTC.
Four digits. Eight guesses. Every clue counts.
Same code worldwide. A new one at 00:00 UTC.
Try any four different digits to get your first clue.
Keyboard: arrows to move · digits to fill · N for notes
Each city keeps its own round. Switching cities does not pause the clock.
525 stations across 14 lines, including suburban branches. Type a name and press Enter.
Korean or English. Spaces, hyphens, capitalization and the station suffix do not matter. Same-name stations fill together. No penalty for wrong guesses. The clock keeps running when you switch games or close the app.
Drag to move. Pinch or use + / − to zoom. Keyboard: arrow keys, + / −, Home. The rivers, coast and regions are your clues.
Map data © OpenStreetMap contributors · ODbL 1.0. Additional station coordinates: Wikidata (CC0). Names and line order: Seoul Metro. Adapted by Play Gridlark. River widths and rail connections are simplified. Download adapted data (includes answers)
A simplified branch-by-branch view. Swipe sideways on small screens. Line codes above a blank are interchange hints. Choose another line above to change these strips.
Lines 1–9, Suin–Bundang, Gyeongchun, Gyeongui–Jungang, AREX and Gimpo Goldline. Includes the Seoul Station, Imjingang and limited Gwangun Univ. branches. Other lines, ITX services, Dorasan and future extensions are excluded. Transfers count once; the two Sinchon stations and two Yangpyeong stations are separate places. The map uses real locations with simplified station-to-station connections, not every service stopping pattern. Optional strips show quiz order, not geography.
Web preview: refreshing this page resets the round. City quiz results do not change your logic puzzle score.
Station names and branches checked against Seoul Metro Cyber Station in Korean and English on 11 September 2026. Geography: OpenStreetMap contributors, adapted under ODbL 1.0, with 18 station coordinates from Wikidata (CC0). Transfer platforms are merged into one quiz point. Same-name Sinchon and Yangpyeong stations remain separate locations. Regional labels and river widths are illustrative; no official affiliation or journey-planning guarantee.
Both current and selected common older names are accepted, including Bulamsan / Danggogae and Jayang / Ttukseom Resort. The adapted data is available from the map credit. No live tiles or location tracking.
Longer answers. A little more to think about. Try Long Words, or warm up with Classic.
Type A–Z. Tap a selected cell again to switch direction. Arrow keys move; Enter goes to the next clue.
Web preview: progress stays while this page is open. Refreshing resets these minis. Checks and reveals are recorded separately. No lives or points to lose; these minis do not change your logic puzzle score.
Tap to toggle X. Double-tap for a star. Drag from an empty cell to mark Xs, or from an X to erase.
Tap X again to clear it. Keyboard: Space marks X, Enter places.
A wall marked 0 rules out bulbs in all its directly adjacent open squares.
Start with numbered walls that have exactly enough available neighbors. Then find dark squares that only one bulb can reach.
Play free in your browser. Pick a game to open its board and rules.