Easy Shikaku puzzles fit on a 4x4 grid of 16 cells, contain exactly five numbered clues whose values (4, 4, 3, 2, and 3) sum to the full board area, and finish at exactly 1,000 points when five non-overlapping rectangles each carry one clue equal to its cell area. Nikoli describes the Shikaku rule set as a rectangle partition where each clue specifies the area of its containing region, and Simon Tatham's maintained Rectangles documentation confirms those same core constraints as an independent reference point. The compact grid keeps the arithmetic gentle: a clue of 4 leaves at most two plausible shapes, a clue of 3 narrows further, and a clue of 2 is essentially forced. Because the clues already add up to 16, every accepted rectangle uses all the cells it claims, and the remaining open space inherits the leftover clues with fewer degrees of freedom. That compact accounting makes a small Shikaku board the natural on-ramp for anyone who wants to see the puzzle's logic in action without committing to a 10 by 10 grid of overlapping candidates.
That on-ramp is exactly what the Lizely Shikaku tool offers. It loads in the browser, ships with one authored 4x4 fixture, and has been mechanically verified to admit exactly one valid partition, so an easy first solve is reproducible rather than a lucky guess. Because nothing is sent to a server and no daily puzzle is fetched, the same opening board shows up on every visit, which is the simplest possible way to repeat a short puzzle until the steps feel obvious.
What Counts as an "Easy" Shikaku Puzzle
Easy in Shikaku rarely means trivial. It means a small grid, a small clue set, and constraints that leave little room for ambiguity. The published Lizely Shikaku board checks each of those boxes: a 4x4 footprint, only five clues, and a unique partition under the same rules Nikoli originally catalogued for the genre. On a 6x6 or 8x8 board the same rules produce dozens of viable rectangles per clue and the search space grows enough that experienced solvers benefit from marking notes. On a 4x4 board the rules are tight enough to settle by inspection within a few minutes.
The clues themselves carry the difficulty weight. A clue of 2 forces a one-by-two domino. A clue of 3 limits the region to a one-by-three strip in either orientation. A clue of 4 opens up two shapes that any subsequent placement can usually rule out. Because the sum of the clues equals the board area, no solving technique has to invent extra candidates — every rectangle you commit to simply narrows the remaining open space for the other four clues. Beginners can therefore practice the pure logic of the genre without juggling strategies they would later develop on larger boards, which is also why dedicated 4x4 boards tend to be the first size shown in beginner tutorials.
The 4x4 Board Layout and Clue Math
Read the published Lizely fixture as five cells holding clues and eleven cells holding no clue at all. The clue values are 4, 4, 3, 2, and 3, and the proof of the puzzle's uniqueness came from enumerating every in-bounds axis-aligned rectangle for each clue whose area equals the clue and which contains no other clue. The candidate counts per clue are 2, 1, 3, 2, and 1, which already telegraph where the puzzle locks down early: the single-candidate clues admit only one in-bounds shape, and once they are placed the rest of the board is largely decided. The table below summarises the per-clue options that the verification step actually counted.
| Clue | Area required | Possible shapes | In-bounds candidates |
|---|---|---|---|
| 4 | 4 cells | 1x4 strip or 2x2 block | 2 |
| 4 | 4 cells | 1x4 strip or 2x2 block | 1 |
| 3 | 3 cells | 1x3 strip | 3 |
| 2 | 2 cells | 1x2 domino | 2 |
| 3 | 3 cells | 1x3 strip | 1 |
The total area covered by the five clues is 4 + 4 + 3 + 2 + 3 = 16, which equals every cell on the board exactly once. That arithmetic guarantee is what lets the puzzle end at exactly 1,000 points: each accepted rectangle awards 200 points, and five correct placements cover the whole 4x4 surface with no gap and no overlap.
Placing Rectangles With Mouse, Touch, or Keyboard
The published control scheme mirrors the rule set rather than reinventing it. Two paths cover every device, and both feed the same validator, so a mouse session and a keyboard session are scored identically.
- Open the Lizely Shikaku tool in any modern browser.
- Tap or click one corner cell of the rectangle you intend to place. A live preview highlights every cell between that corner and wherever the pointer next moves.
- Tap or click the opposite corner cell to define the second anchor. The preview now shows the full candidate shape covering every cell in that span.
- Choose Place rectangle to submit. If the span is wrong, choose another corner or press Escape to cancel and start over.
- Keyboard players move the cursor with the Arrow keys, press Enter once to anchor the first corner, navigate to the opposite corner, and press Enter a second time to place immediately. U removes the most recent accepted rectangle without clearing the recorded mistake count, and Escape cancels a partial selection.
The mobile-friendly layout keeps four equal columns and large selection controls so touch play does not depend on drag precision. The keyboard path covers every action a mouse can perform, including dismissal of an invalid submission, so desktop players can avoid reaching for the trackpad once they learn the shortcut set. A double-press of Escape still opens the boss screen on every device, which is useful when the short puzzle is played in a shared workspace.
Validation Rules and Scoring
Every accepted rectangle is checked against the same five predicates: it must stay inside the board, contain exactly one numbered clue, have an area equal to that clue, and overlap no rectangle already accepted. The check runs on submission, not before drawing, which lets players iterate with the live preview without locking themselves out of an experiment.
An invalid submission does not partially place. It stays unplaced, registers as one mistake, and lets you inspect the feedback before trying again. A second invalid submission deadlocks the run until you Restart, so two careless clicks end the attempt regardless of how close the third click would have been. Accepted rectangles stay visible throughout the run, so Undo always removes the most recent accepted rectangle without erasing the recorded mistake count. This separation of "wrong guess" from "wrong placement" lets players use Undo as a planning tool on boards that look straightforward but turn out to be more entangled than expected.
| Event | Score change | Run state |
|---|---|---|
| Accepted rectangle | +200 points | Puzzle continues |
| First invalid submission | No change | One mistake recorded |
| Second invalid submission | No change | Run deadlocks until Restart |
| Undo on accepted rectangle | -200 points | Puzzle continues |
| Fifth rectangle covers 16 cells | +200 points | Puzzle frozen at 1,000 points |
Once the fifth valid rectangle covers the entire 4x4 board, the puzzle reaches the terminal completion state. Any later cursor movement, placement attempt, or Undo press cannot change the frozen 1,000-point result. Restart returns the board to its original clues, zero score, zero mistakes, no selection, and no accepted rectangles, which is also the easiest way to repeat the run while practising the same five-step route from scratch.
A Solving Route for Beginners
Begin with the clue that admits the fewest rectangles, then work outward. On the published Lizely fixture, the single-candidate clues each force a one-in-bounds shape that must be placed immediately — leaving those spaces open while investigating a more flexible clue wastes the leverage they provide. After each accepted rectangle, recount the open cells around every remaining clue: a clue that started with three options may now have only one, and that new constraint is the next move.
The clue arithmetic doubles as a planning tool. A clue of 4 sitting in an open three-by-three corner is obviously a one-by-four strip; the same clue wedged between two already-placed rectangles has nowhere to go except a 2x2 block. Reading the board at each step and matching the clue value to the leftover shape is the entire skill, and the five-clue total of 16 guarantees there is always room to fill. Use Undo on a legal choice that blocks the remaining space rather than treating it as a defeat — a removed accepted rectangle restores its 200 points in the negative direction, but the puzzle remains live and the mistake count is not touched, so a correction costs nothing but a click.
Aim for the reproducible 1,000-point finish rather than the fastest time. Completion time is intentionally not scored, and the fixed board becomes easier after repetition, so a deliberate second run through the same five rectangle placements is a better practice drill than racing the clock. Players who like the no-download route can also read the companion guide on playing Shikaku without downloading for an overview of the browser-first setup.
Why the Fixture Has Only One Answer
Mechanical proof, not human pattern-matching, determined that the published 4x4 board admits one and only one rectangle partition. The verification pipeline enumerates every in-bounds axis-aligned rectangle for each clue, retains only those whose area equals the clue and which contain exactly that one clue, sorts the resulting candidate sets by size, and runs an exact-cover backtracker that rejects overlapping cells and accepts only covers containing one rectangle per clue plus complete board coverage. The release test asks the backtracker for up to two valid covers and receives exactly one.
That unique answer uses a 2x2 block in rows 1-2 and columns 1-2, a 2x2 block in rows 1-2 and columns 3-4, a 1x3 strip across row 3 and columns 1-3, a 2x1 strip in rows 3-4 and column 4, and a 1x3 strip across row 4 and columns 1-3. The same runtime then rechecks each rectangle's clue count and area, the absence of overlap, complete board coverage, exact 1,000-point scoring, out-of-range rejection, area-mismatch rejection, Undo behavior, two-error deadlock, and frozen completion and deadlock states, so the single answer is reproducible locally and in any production browser.
Beginners who want the friendly entry point can return to the Shikaku tool, follow the five-step control scheme above, and trust that any discrepancy between their attempt and the published answer is a signal to undo and try the other shape — every valid move is already on the board by the time the clue values settle below 1,000 points.
Related reading: How to Choose Your Next Step in Shingoki Puzzle.