tetryst

Tetryst

Play it here: mattafaak.github.io/tetryst

A browser-based Tetris clone in TypeScript. Single-file build, no installation.

# Play offline (macOS / Linux)
curl -fsSL https://mattafaak.github.io/tetryst/ -o tetryst.html
open tetryst.html

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How to play

Key	Action
← →	Move
↓	Soft drop (1 point per row)
Space	Hard drop (2 per row, locks instantly)
↑ X	Rotate clockwise
Z	Rotate counter-clockwise
C Shift	Hold — stash the current piece for later
P Esc	Pause
M	Mute

On the menu, ← → changes the game mode. ↑/↓ adjusts the starting level in Marathon. Hit Enter to start.

If you pause, ↑ ↓ navigates between Resume, Restart, and Quit to Menu.

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Game modes

Mode	Goal
Marathon	Reach level 15. Gravity speeds up as you go — starts at 1 row/second, ends at 200 rows/second.
Sprint	Clear 40 lines as fast as you can. Gravity stays slow the whole time.
Ultra	Score as much as possible in 3 minutes.

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Scoring

Line clears are the main event:

Lines	Base
1 (Single)	100 x level
2 (Double)	300 x level
3 (Triple)	500 x level
4 (Tetris)	800 x level

A T-Spin is when you wedge a T-piece into a gap using a wall kick (not just rotating it in open air). It scores more:

	No lines	Single	Double	Triple
T-Spin	400	800	1,200	1,600
T-Spin Mini	100	200	—	—

Back-to-back (B2B): Chain two difficult clears (Tetris or T-Spin) and the second gets a 1.5x multiplier. A single line clear breaks the streak.

Combo: Every consecutive piece that clears lines adds 50 x combo count x (level + 1).

Perfect Clear: Clear the entire board at once — 800-3,200 x level depending on how many lines.

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How leveling works

Marathon doesn't just count lines. Difficult clears count for more:

Clear	Effective lines
Single	1
Double	3
Triple	5
Tetris	8
T-Spin Double	12

You need 10 effective lines for the next level. One T-Spin Double levels you up. One Tetris almost does. Back-to-back clears give a 1.5x multiplier on effective lines too.

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Guideline compliance

This is a full implementation of the 2009 Tetris Design Guideline. Every mechanic listed below is verified correct against the spec.

7-bag randomizer. Older Tetris was pure random, so you could get five Z-pieces in a row. This shuffles all 7 pieces into a bag, deals them one at a time, then reshuffles. Every 7 drops you get exactly one of each shape. The first piece is always I, J, L, or T (never O, S, or Z, which are harder to place on an empty board).

SRS (Super Rotation System). The official rotation standard. All 8 rotation transitions for JLSTZ pieces and all 8 for the I-piece use the exact TDG kick tables. Try to rotate near a wall and the piece kicks sideways 1-2 cells to make room. The O-piece has no kicks.

T-spin detection (3-corner rule + kick exception). The game checks the four diagonal corners of the T-piece's 3x3 bounding box. 3 or more occupied corners and it's a T-Spin; if only the two front corners are occupied, it's a Mini. Kick tests 4 and 5 (the last two wall-kick offsets) always produce a full T-Spin regardless of the corner check — this is the TDG kick exception.

Lock delay with extended placement. When a piece touches the ground, you have 500ms before it locks. Moving or rotating resets that timer, up to 15 times per piece. If the piece falls to a new lowest row, the reset counter is cleared — so you can keep stalling as long as you keep moving down.

IRS (Initial Rotation System). Press a rotation key during the entry delay or line-clear animation and the next piece spawns already rotated. Works for both clockwise and counter-clockwise.

IHS (Initial Hold System). Press Hold during the entry delay or line-clear animation and the next piece is immediately swapped into the hold slot on spawn.

DAS/ARR. Hold left or right: the piece moves once, waits 300ms (DAS), then slides every 50ms (ARR). Soft drop has no initial delay and repeats at 50ms. These match the TDG reference timings.

Gravity curve. 16-level speed table from 1000ms/row (level 0) down to 5ms/row (level 15). Gravity accumulates across frames so the piece drops the correct number of rows even at extreme speeds.

Lock-out and block-out. Lock-out: a piece that locks entirely in the 20-row hidden buffer above the visible field ends the game. Block-out: a newly spawned piece that overlaps existing blocks ends the game.

Ghost piece. A faint outline showing exactly where the piece lands if you hard drop.

5-piece next queue. Within the TDG-specified range of 4-6.

Hold. Swap the current piece with storage. Once per piece drop.