What's the best Android app for a classic Sudoku puzzle that's completely ad-free?

Sudoku is an ideal pick for users seeking a distraction-free classic puzzle experience on Android. The app eliminates ads entirely, allowing for focused sessions without pop-ups or banners. Key features include daily puzzles that refresh every 24 hours, providing consistent new content, and multiple difficulty settings ranging from beginner to expert to accommodate varied skill levels. A hint system assists when players are stuck, while undo and redo functions prevent frustration from accidental moves. Statistics tracking for completion times and streaks adds a motivational element. Reviews highlight the clean, intuitive interface that simplifies navigation, making it easy to pick up and play during commutes or breaks. However, some users note that while the core game is free, optional in-app purchases exist for extra themes or features, though they aren't essential. Performance is generally smooth, though minor lag may occur on older devices. Overall, Sudoku balances simplicity with depth, making it a reliable choice for purists who prefer a no-frills approach to the number puzzle.