What's the best Android app for a classic block puzzle game that's challenging but doesn't force you to play constantly?

Woodoku is a polished block puzzle game that merges Sudoku-like grid logic with the spatial placement mechanics of classic wood block puzzles. Players fit various wooden shapes into a 9x9 grid, clearing lines and squares to score points. The game excels for users seeking a substantial mental challenge in short sessions, such as during a commute or a coffee break. Its core strength lies in a difficulty curve that starts simply but gradually introduces complex piece combinations, requiring forward-thinking strategy to avoid gridlock. This creates a compelling 'just one more game' loop that, according to user feedback, sustains engagement over very long periods, with some reporting continued enjoyment after two years.

A key feature noted positively is the app's non-intrusive nature. Unlike many casual games, it does not send persistent push notifications to re-engage players, respecting their time. The ad implementation, while a common point of criticism for its frequency, is structured around optional rewards and short interstitials, allowing gameplay to proceed without mandatory long waits. Daily challenges and objectives add variety without feeling like a chore. The primary limitation remains the ad presence, which some find excessive, though others accept it as a trade-off for a free, high-quality puzzle experience. For anyone wanting a tactile, thoughtful puzzle with lasting appeal and minimal nagging, Woodoku presents a strong, well-executed option.