Sudoku.com by Easybrain Ltd positions itself as one of the most downloaded sudoku applications on iOS, offering thousands of classic number puzzles designed for mental stimulation and relaxation. With millions of daily users globally, the app caters to both novice players and seasoned enthusiasts through its scalable difficulty system and clean digital implementation of the classic paper-and-pencil game. The application's core functionality includes multiple difficulty levels ranging from easy to expert, automatic error checking that prevents incorrect entries from disrupting the entire board, and hint systems that assist players without revealing complete solutions. The digital interface replicates traditional sudoku mechanics while adding quality-of-life improvements like automatic pencil marking and number highlighting. These features collectively eliminate the physical limitations of paper sudoku, particularly the need for frequent erasures or manual verification of number placements. User experience centers around a minimalist interface with clear number pads and grid highlighting that indicates rows, columns, and 3x3 boxes. Real-world usage patterns show the app serves both quick mental breaks during daily routines and extended puzzle-solving sessions. The color-coded highlighting system, while functional, has drawn some criticism for its limited customization options according to user feedback. Navigation remains straightforward with quick access to new puzzles and progress tracking, though the absence of cloud saving limits continuity across multiple devices. User reviews consistently praise the app's engaging puzzle design and convenience over physical sudoku, with reviewer Divahustla noting on September 2, 2025: 'Easier than wasting paper or having to erase so much.' However, multiple reviews from August 31 to September 2, 2025 (including Klmcm.24 and Holy angel) highlight intrusive advertising frequency as a primary drawback. The absence of native cross-device synchronization also emerges as a limitation, with nightarrow17 specifically requesting cloud save functionality on August 31, 2025. The application demonstrates strengths in puzzle variety and accessibility but faces significant limitations in its advertising implementation and lack of progress synchronization. Ideal for casual players seeking convenient mental stimulation, though serious enthusiasts may find the ad frequency and device-limited progress tracking restrictive. The 4.76/5 rating reflects generally positive reception despite these persistent usability concerns.