Shikaku Ultimate is a free puzzle game for Android developed by Celtic Spear. The game is based on a classic Japanese puzzle called Shikaku or Rectangles. The objective of the game is to divide a rectangular grid into square or rectangular pieces, each containing one number. The number represents the area of the piece. The game is challenging and addictive, with colorful graphics and a simple interface.

In Shikaku Ultimate, the game has evolved to include different shapes that can be drawn on the grid, making it more challenging and exciting. The game is also known as "Divide by Squares" or "Divide by Box".

Overall, Shikaku Ultimate is a fun and challenging puzzle game that is perfect for anyone looking for a new brain-teasing challenge.