TappyPotato logic puzzles

Pencil logic

LITS — rules and where to play

LITS · Lits / Tetromino Puzzle / Four-Cell Shapes

Carve one L, I, T or S tetromino out of every room. Four shapes, one per room — the most elegant of the region-division family.

Origin
2004 · Japan
Difficulty
★★★★★ 3–5 / 5
Time
10–40 min
Grid
8×8 – 20×20
Sites
11

Rules

  1. Shade exactly four cells in each outlined room, forming an L, I, T or S tetromino (rotations and reflections allowed).
  2. No 2×2 block of black cells.
  3. All black cells must be connected.
  4. No two rooms may hold the same shape in the same orientation where the rule set states it.

How to start

Solve the small rooms first

A four-cell room is locked whole; a five-cell room has only a few cuts.

The 2×2 ban rules out squares

Any four cells forming a square is not a legal piece.

Thread the rooms with connectivity

Late on, "the blacks are one region" is what pins each remaining choice.

Where players get stuck

  • Treating the O (2×2 square) as a legal shape.
  • Forgetting all black cells form one connected region.

Play LITS

11 sites
Puzzle PicnicFree

Handmade Nikoli-style grids from a mix of setters, picked rather than dumped, playable in the page.

Open → PuzzleMixFreemium

Gareth Moore's site: Sudoku, then Slitherlink, Nurikabe, Futoshiki, Calcudoku and Hanjie.

Open → pzv.jpFree

A wider puzz.link-style database — more types, cut a bit finer.

Open → Penpa+Free

A fat editor for Japanese types: lots of shapes and marks, and it will ingest a puzz.link.

Open → pzplusFree

A community bank with difficulty and clear counts, browsable without leaving the page.

Open → Naoki InabaFree

Naoki Inaba writes a lot, including types you won't see many other places.

Open → Puzzle Square JPFree

A large Japanese variant archive that moves often, with difficulty marks on the grids.

Open → Grandmaster PuzzlesFree

Thomas Snyder's own handmade Sudoku and variants — world-champion difficulty, not generated filler.

Open → Puzzle LITSFreemium

Puzzle Team LITS specialty — daily grids and a deep bank in the same UI family.

Open → GridPuzzleFree

Dozens of grid logic types in the browser, with progress tracking and dailies.

Open → LITS (CN)Freemium

Puzzle Team LITS in Chinese — same specialty bank, Chinese UI.

Open →

Browse Japanese pencil puzzles →

Also on multi-type portals

Janko.atFree

Otto Janko's German/English archive: hundreds of playable types, all free.

Open → Puzzle RulesFree

Clean rule pages for dozens of types. Fastest way to learn a grid you haven't seen.

Open → NoqxFree

An ASP solver for 170-plus types. Connectivity puzzles tend to come back quickly.

Open → Nikoli Puzzle SolverFree

Z3 under the hood, 100-plus types, including hex and triangle boards.

Open →

Browse portals →

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About this page
  • Last updated 2026-09-22
  • Source Curated compilation of established puzzle rules and listed third-party play sites
  • Audience Players learning LITS rules or looking for online sites to play
  • Covers Rules summary, how to start, common pitfalls, and the dedicated play sites listed on this page
  • Does not cover Hosted puzzles, worked solutions, official contest rankings, third-party uptime or pricing guarantees
  • Not advice This page is puzzle reference content only. It does not constitute financial, legal, medical or other professional advice.
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