Added modes: Skyscraper Sudoku, Skyscraper Sudoku (4x4)
Added Practice Mode for all frame-based Sudoku variants
Added Workshop support for all frame-based Sudoku variants
Added Master difficulty for Classic Sudoku and Frame Sudoku — unlocked after completing 30 puzzles per mode
Added achievement support for Butterfly Sudoku and Skyscraper Sudoku
Added Daily Challenge Steam Leaderboard — view global completion times, average time, and rankings
Added Auto Pencil Marks — automatically fill candidate numbers for empty cells (enable in Settings)
Improved: Draft (candidate) toggles, paste, and auto-fill are now included in the undo/redo system
Added: M key to auto-pencil candidates for the currently selected cell
Added: Frame Sudoku combination hints — select a border cell to view possible number combos with manual exclusion
Fixed: Product Sudoku — second diagonal clue not rendering when two clues overlap at the same corner
Other: Further refined controls and UI polish