Built a single-file math crossword game with 5 themed puzzles and 100 clues using vanilla HTML/CSS/JS - no build tools, no dependencies. The trickiest part was implementing keyboard navigation (arrow keys, tab-to-toggle, auto-advance) while keeping movement locked to the current word. Grid generation and clue numbering work well enough, though the data format is hand-crafted rather than auto-generated. Mobile layout is functional but needs polish; localStorage save and a timer are next on the list. Overall it’s a working v1.0 that runs anywhere you can open a browser.