1. Added 30 Killer Sudoku levels, including 10 easy, 10 medium, and 10 hard levels.
2. Stored cage candidate number markings.
3. Optimized the arrangement of cage candidate numbers.
4. Fixed a bug with quick marking of candidate numbers.
5. Removed the blue selection box toggle feature to enhance the interface's aesthetic appeal.
V2.2 Added More Killer Sudoku Levels and Optimized the Gaming Experience.
Source: Steam Community (opens in a new tab)