requirements.md

on page load

• fetch new game from API
• check localStorage for existing user data
• if user data differs from original data, show this difference in UI
• get difficulty from localStorage, default to "easy"

dipsplay tip at the start of the game

• click on 'x' to close tip modal
• persist user state in localStorage to hide tip on refresh

user can select cell by clicking

• in UI: highlight all columns, rows and subgrids that contain user selected cell
• 1) if cell is empty, only show highlights as listed above

user enters a number by keyboard

• if number is valid - highlight as default
• if number is invalid - highlight all matching numbers in all columns, rows and subgrids that contain the user's number
• display incorrect input in red font, red background for matching colors

user enters an arrow key (up, right, down, left)

• switch focus

Non-board related features

• on completion a message is displayed

• button below board for selecting difficulty and resetting the board

• game header displays current difficulty

• Timer

• internationalization

• demo button to show UX as game ends