How to Play Shikaku Step by Step

Every numbered cell belongs to one rectangle. That rectangle must satisfy three conditions at the same time:

1. It must be a true rectangle.
2. It must contain exactly one clue number.
3. Its area must match the clue value.

Then one more rule applies to the full board: all rectangles together must cover the entire grid with no overlap and no gaps.

That is the whole puzzle. The difficulty comes from deciding which rectangle belongs to which clue.

Start by looking at the numbered cells one by one. Each number tells you the area of its rectangle, not the exact shape.

For example:

• A clue of 1 can only be a 1x1 rectangle.
• A clue of 2 can be 1x2 or 2x1.
• A clue of 4 could be 1x4, 2x2, or 4x1.
• A clue of 6 could be 1x6, 2x3, 3x2, or 6x1.

At this stage, do not try to solve everything. Just understand what each clue is asking for.

Once you know the possible factor pairs, ask which of those shapes actually fit on the board.

A clue near an edge cannot stretch in every direction. A clue near a corner is even more restricted. A clue next to another number may lose legal options because one rectangle cannot contain two clues.

This is where Shikaku becomes a real logic puzzle. You are not only matching a number to an area. You are matching an area to a legal position.

The easiest early deductions usually come from constraints.

A clue in a corner often has fewer possible placements because part of the board is already blocked by the outer border. A clue on the edge has fewer directions available than a clue in the middle. Small clues such as 1, 2, or 3 also tend to have fewer legal shapes.

It also helps to look at clue groups instead of isolated cells. If two clues are close together, their rectangles compete for the same space. That competition often reveals a boundary earlier than you expect.

As you confirm rectangles, the board becomes easier to read.

Each solved region removes cells from the rest of the puzzle. That changes what nearby clues can still do. Large clues that looked vague at first often become much clearer later because the board has less open space left.

Keep checking both local and global logic:

• Is this rectangle legal for its clue?
• Does it avoid other clues?
• Does it leave the remaining board workable?

A move that looks fine in isolation can still create bad leftovers somewhere else.

Imagine a small board where a clue 1 sits near the top. That clue is fixed immediately because its area must be one cell.

Nearby, a clue 2 sits on the left edge. Because it is on the edge, maybe only one or two placements fit. If one option would swallow another clue or run off the board, that option disappears.

Now suppose a clue 6 in the middle still has several possible shapes. You do not need to solve it yet. Let the smaller and tighter clues reduce the open space first. When the board gets more crowded, the 6 will often become easier.

That is the basic rhythm of Shikaku: solve what is constrained, let the board tighten, then return to the flexible clues.

The most common mistake is treating the clue value as the only rule. A rectangle with the right area can still be wrong if it includes two clues or damages the remaining board.

Another mistake is trying to solve the biggest clue first just because it looks important. In many boards, large clues are easier to place later, not earlier.

A third mistake is guessing too soon. If two placements look equally possible, it often means you should look somewhere else first.

If you have just learned the basics, the best next step is to play a few smaller boards in Practice mode. That gives you time to understand the flow without daily pressure.

After that, you can move into the Daily puzzle when you want one clear board to solve each day. And if you want help checking a clue layout or testing whether a board is valid, the Solver can help with that too.

Shikaku feels much easier once you stop seeing it as a wall of numbers and start seeing it as a series of rectangle decisions. Learn what each clue asks for, use the board to remove impossible shapes, and let the puzzle narrow itself. That is the core of how to play.