- Add removedCells to GameOptions for custom puzzle sizes
- removedCells overrides difficulty default when provided
- Maintain backward compatibility with all defaults
- Complete IMPLEMENTATION.md with Iteration 16 and summary
- Completely rewrite README.md with comprehensive documentation:
- Complete API reference (GameOptions, GameManager, CursorManager, ScoreManager)
- Game states and state machine flow
- Full VIM controls reference (movement, editing, hints, game control)
- Cell state rules and visual feedback
- Detailed scoring formula with examples
- Game-over conditions (time and hint limits)
- Hint system priority and penalties
- Configuration examples for different play styles
- Platform hook integration guide
- Mark implementation as COMPLETE and PRODUCTION READY