Rules & objective
Retains this project’s original basic profile: full 10 columns/20 rows, seven tetrominoes drawn independently with equal probability, not a seven-bag. Every 500 ms move down one cell; if blocked, lock. Move left/right or rotate clockwise; reject collisions/out-of-bounds with no wall kicks or hold. Hard drop locks immediately. Clear all full rows, 100 points per row; no extra points for movement/soft/hard drops. A blocked fixed-position top spawn ends the run; no early victory target. Pause, rules and hidden page stop gravity; resume does not catch up hidden time. New run clears board/score and draws fresh pieces. The preview shows the next piece. Space/Enter on buttons activate them normally; Space on the board hard-drops.
Undo returns before the last lock and pauses. Redo retains observed pieces. Zoom pauses for panning; Resume fits the full board. Restart retains drawn pieces; New draws fresh. Progress stays in this browser.
Controls
←→ move · ↑ rotate · ↓ step · Space hard drop · P pause/resume · R new run
Worked example
A row clears only when all ten cells are filled. This edition has no wall kicks, so move a piece away from a wall before retrying a blocked rotation.