Undercell: Logic Puzzle

Upside Dariusz Majewski

About this game

Undercell is a pentomino puzzle in the Pentopia genre. Find the five-cell pieces hidden on the board, using the arrow clues around them. Every board has one solution and can be solved without guessing.

Use the sensors:
• A sensor's arrows point toward the nearest cells belonging to a piece.
• Pieces never touch, even at a corner.

Add Piece and Empty notes as you reason. Then lock one cell or a connected marked group. If all the locked cells belong to pieces, they open together. Locking one empty cell ends the board.

Features:
• Twelve difficulties: 6×6, 8×8, and 10×10 boards in easy, medium, hard, and extra-hard.
• Larger locks earn more points. On the same board, a five-cell lock earns five times as much as five one-cell locks.
• A harder difficulty pays more for the same lock, and a bigger board pays more because it holds more pieces.
• Earn up to three stars based on hint use. Successful locks earn points toward a persistent rank.
• Each hint names one forced cell and explains the reasoning step by step.
• When the hint counter runs out, you can keep taking hints. That board then earns no stars or points.
• Save boards and share challenge codes without sharing your progress or the solution.
• Built-in tutorial, light and dark themes, sound, haptics, keyboard controls, and screen reader support.

Undercell works offline. It has no ads, no accounts, no analytics, and no in-app purchases.

What’s new

How to play now shows its six boards in a clearer order.

The board that proves a Piece note and an Empty note at once now comes last, after the two boards that each prove one.