Tetra Strategy: Rotation Quirks, Speed Curve and Four-Row Clears

Updated October 2026

Tetra is a compact block-stacking game: seven four-cell shapes fall into a well ten cells wide and sixteen tall, and complete rows vanish. Generic advice about keeping your stack flat applies, but this version has its own rules that change how you should play. There is no preview of the next piece, rotation never nudges a piece away from a wall, and the well is noticeably shorter than many players expect. This guide covers those details and builds a plan around them.

The rules the code actually uses

Every piece is chosen at random from the seven shapes, each with the same one-in-seven chance, independently of the previous pieces. There is no bag that guarantees each shape appears regularly and no hold slot, and you never see what comes next. A new piece appears at the very top with its lowest row in the top row of the well. The long bar and the three-wide shapes start over columns 4 to 6 or 4 to 7, counting from the left, and the square over columns 5 and 6.

Gravity moves the piece down one row per tick. When the piece cannot move down any further, the next tick fixes it in place, clears any complete rows and spawns the next piece. If that new piece overlaps existing blocks, the game ends. Because pieces appear in the top row, the game effectively ends as soon as your blocks reach the top row in the middle columns where new pieces arrive.

Scoring depends only on how many rows one piece completes: 100 for one, 300 for two, 500 for three and 800 for four. There are no points for dropping, and the values do not grow with speed. Per row, that is 100, 150, about 167 and 200 points.

How fast it gets

The tick starts at 700 milliseconds and shortens by 25 milliseconds for every row you have cleared, reaching 110 milliseconds at 24 rows; after that it keeps shrinking by 2 percent per row, to about 65 milliseconds at 50 rows and 24 at 100. A piece that falls the whole height of the well therefore takes about 11 seconds at the start, about 7 seconds after 10 rows, about 3 seconds after 20 rows and under 2 seconds at 24 rows, and it keeps getting faster from there.

This curve is steep. Most of the speed-up happens in the first two dozen rows, which on a ten-wide board is not many pieces at all. Early decisions about the shape of your stack carry over into a phase where you have very little time per piece, so build good habits before the speed arrives rather than after.

The game has no pause button, but the falling piece waits while you are away: switch to another app or lock the phone and gravity stops until you come back. It does not stop while the page is on screen, so look away only between pieces.

Controls and their limits

• Drag sideways to move. The piece moves one column for every cell width your finger travels, so a single long drag can carry it across the whole well.
• Tap to rotate clockwise. A tap must be short and nearly still; a press that moves too far or lasts too long is not treated as a tap.
• Swipe down for a hard drop. The piece falls straight to the bottom and is fixed almost instantly, so there is no chance to slide it afterwards.
• On a keyboard, the arrow keys move and rotate, the down arrow steps the piece one row, and the space bar hard-drops.

Without a hard drop, a landed piece stays movable only until the next tick. At the slowest speed that is up to 0.7 seconds; at full speed it is 0.11 seconds, too short for a reliable correction. At high speed, plan the final position before the piece touches down.

Rotation is anchored to the top-left

When a piece turns, the game rotates its shape inside its bounding box while keeping the box's top-left corner in place. Nothing is shifted to make room. If the rotated shape would overlap a wall or a block, the rotation simply does not happen.

Two practical consequences follow. First, pieces appear to drift as they turn. A flat long bar that turns upright becomes a column in its leftmost cell, and turning it back puts it in the same four cells as before. Learn where each shape ends up after one, two and three turns, rather than rotating and then correcting.

Second, the right wall is a rotation trap. An upright piece pressed against the right side usually cannot turn, because the turned shape is wider and would stick out of the well. The left wall has no such problem, since rotation extends to the right. The easy fix is to rotate first, while the piece is near the centre, and move it to the right only after it has its final orientation.

Stacking for a sixteen-row well

A short well leaves less room to recover. If your stack is ten rows tall, only six rows remain for a fresh piece to arrive and be placed, and at full speed that is under a second. Keep the stack low and treat anything above the middle as an emergency where you clear rows, even singles, until it comes down.

• Keep the surface stepped, not spiky. Height differences of one cell between neighbouring columns accept most shapes. Single-width gaps two or more cells deep only accept the long bar or an upright L or J.
• Avoid covering holes. A hole under a block cannot be reached until the rows above it are cleared, and each one makes a clean clear harder.
• Give every shape a home. Before each piece, glance at the surface and make sure there is somewhere acceptable for the S and Z shapes. They are the ones that create holes when the surface is flat.

When to go for four rows

Four rows at once pay twice as much per row as singles, so a well kept open in one column is the standard high-score plan. In this version it carries a specific risk: with no preview and pure one-in-seven odds, the long bar can stay away for a while. The chance of seeing no long bar in the next 14 pieces is about 11 percent, and in the next 20 pieces it is still about 5 percent.

A sensible rule is to build towards a four-row clear only while the stack is low, and to abandon the plan as soon as the stack passes about half the well. Filling the open column early with an upright L or J costs you points but not the run. The open column can be on either side, but turn the long bar upright near the centre before you carry it over, because once it stands against the right wall it can no longer be rotated.

A practice plan

1. Play a few slow runs with the goal of never creating a hole. Ignore the score.
2. Learn the rotation positions of each shape near the centre of the well so you stop over-rotating.
3. Practise moving a piece to its final position with one smooth drag, then hard-dropping.
4. Once you reliably pass 24 rows, add an open column on the left and go for four-row clears while the stack is low.

Your best score is saved on this device when the game ends, and the game-over card offers to send your result to the Hall of Fame. Since the speed stops climbing at 24 rows, a run that survives that point depends entirely on how cleanly you stack.