Block stacking with the Super Rotation System and its real wall kicks, so a flat I can stand up off the floor, and a 7-bag randomiser so no piece is ever more than twelve away. Hold, ghost piece and Guideline scoring.
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Snake with four modes, four power-ups and the classic tail rule: the square your tail is leaving is safe to enter, which is what lets you turn tightly inside your own body. Four speeds, per-mode high scores and touch controls.
Minesweeper on the three standard boards or one of your own, with both first-click conventions offered by name: a safe square, or a safe square and its eight neighbours. Flags, question marks, chording and best times.
Slide tiles to combine them and reach 2048. Each tile merges at most once per move, checked exhaustively against the rule, and the board total printed under the grid always equals everything ever spawned. Undo, touch controls and score tracking.
An I piece is lying flat on the bottom row and you press rotate.
Input
I at rotation 0, resting on the floor · press ↑
Result
It stands up, kicked by offset 4 of 5. The old rotation refused the move entirely.
The Super Rotation System gives every rotation an ordered list of five offsets to try, including vertical ones, and takes the first that fits. The version that used to run here tried five offsets too, but all of them were sideways, so a piece against the floor could never be stood up and the spins the game is known for were unreachable. The page prints which offset each rotation used. The other invisible fix is the randomiser: pieces come from a shuffled bag of seven, so no piece is ever more than twelve away, where independent draws left gaps of up to 97 pieces over 700,000 draws.
Rotate and place falling tetrominoes to complete lines. Two things here are the ones most browser versions get wrong: the rotation is the Super Rotation System with its published wall kicks, so an I piece flat on the floor can stand up and a T can be twisted into a slot; and the pieces come from a shuffled bag of seven, so you never wait more than twelve pieces for the one you need.
Rotating shapes in your head and picking a placement is the exercise; with real wall kicks the mental model you build transfers to any other modern version.
The rhythm of placing pieces is a calm thing until level 8, and the bag means the pieces you need turn up.
A round fits into a break, and nothing is uploaded or saved anywhere but this browser.
The kick readout names the offset every rotation used, which is a way to see SRS working rather than reading a table.
A flat I resting on the bottom row rotated with the up arrow: SRS finds an offset that lifts it clear and the page reports the kick it used. The old rotation, which only tried sideways offsets, refused the same move.
Leave column ten empty and stack flat. From a bag the longest you can wait for an I is twelve pieces, so the four line clear is a plan: 800 points at level 1 against 400 for the same rows singly.
Press C on an early I to put it in the hold slot, then keep stacking. One swap per piece, so the slot is worth spending deliberately.
Ask two Tetris implementations to rotate the same piece against the same wall and you can get two different answers, because "rotate" is not one operation. The version that used to run here transposed the piece matrix and reversed it, then tried shifting the result 0, +1, -1, +2 and -2 COLUMNS until something fitted. Every one of those offsets is horizontal, so an I piece lying flat on the floor could not be stood up at all: standing it needs four rows below its top left corner and the only thing on offer was sideways.
What ships now is the Super Rotation System from the Tetris Guideline. Each piece has four explicitly defined states rather than whatever a transpose happens to produce, and each rotation has an ordered list of five offsets to try, including vertical ones. The first that fits is taken, and the page prints which: "rotated in place", or "kicked by (-2, 1), offset 4 of 5". That is what makes the spins players expect reachable, and it is why the same keypress against a wall behaves the way it does in every other modern version.
The randomiser matters just as much and is even less visible. Drawing one of seven pieces independently each time sounds fair, and it is fair on average, but the wait for a particular piece is unbounded: measured over 700,000 draws, the longest gap between two I pieces was 97 pieces. A bag fixes that. The seven pieces are shuffled and dealt one at a time, then a fresh bag is shuffled, so every seven consecutive pieces are all seven, and the longest possible drought is 12: a piece first in one bag and last in the next. That bound is what makes building a well and waiting for an I a plan rather than a hope. The shuffle is Fisher and Yates over a uniform source, not a comparator returning random noise, which is not a shuffle at all.
Scoring follows the Guideline: 100, 300, 500 and 800 points for one, two, three and four lines, each multiplied by the level, plus a point a cell for a soft drop and two a cell for a hard drop. The jump from 500 to 800 is the whole reason to build a well. Hold really holds, once per piece, and a hard drop LOCKS the piece where it lands rather than leaving it sliding on the floor until the next gravity tick.
Clearing four lines at once, which is 800 points times the level against 400 for the same four lines cleared one at a time. That is the reason to keep a well open on one side.
Because this uses the Super Rotation System, which tries five offsets for every rotation rather than just leaving the piece where it is. The page prints which offset it used, so you can see it happening.
The pieces come from a shuffled bag of seven rather than being drawn independently. Every seven consecutive pieces are all seven, so the longest possible wait is twelve. With independent draws the wait has no bound at all: over 700,000 draws the worst measured was 97.
Yes, on the C key or Shift. It swaps the falling piece for whatever is in the slot, once per piece; the slot dims once you have used it and clears when the next piece spawns.
Yes, immediately. It used to just move the piece to the floor and wait for the next gravity tick, which meant a hard-dropped piece could still be slid sideways.
One second a row at level 1, 100 ms faster each level, with a floor of 100 ms at level 10. The level goes up every ten lines.
The game runs entirely in your browser. No account is needed and no gameplay data is collected.