Sandtris: the website where Tetris blocks crumble to sand

Sandtris is a free browser game where Tetris-style pieces fall into the well and then collapse into loose, flowing sand, and the only way to score is to build an unbroken bridge of one colour from the left wall to the right. It is a single-purpose toy that takes one familiar idea, swaps its rigid rows for granular physics, and quietly becomes much harder to put down than it has any right to be.

In brief

• Sandtris at sandtris.com is a falling-sand take on block stacking: pieces dissolve into coloured grains the moment they land.
• Lines do not clear by filling a row. A same-colour streak that touches both side walls vanishes in an avalanche.
• It was built by Franco Miranda in p5.js, inspired by mslivo's Setris, the Java game that hit the front page of Hacker News in 2023.
• No download, no account, no tutorial. Arrow keys, a weekly leaderboard, and a surprising amount of regret.

What Sandtris actually is

The pitch is small. A tall rectangular well sits in the middle of the page. Tetromino-shaped pieces descend from the top in four colours. So far this reads like every block puzzle since the mid-1980s. The twist arrives the instant a piece lands.

Instead of staying a solid shape, the piece shatters into a cluster of tiny coloured squares, each one an independent grain. Those grains then obey gravity. They slide down slopes, fill gaps, and pile into drifts against whatever is already there. A neat L-piece dropped onto an uneven surface does not sit politely on top. It spills.

The covered site, sandtris.com, states the goal in a single line: connect the same colour across the screen to clear. There are no completed rows to chase. There is only the slow, deliberate work of herding grains of one colour until a continuous band of them spans the well from edge to edge.

Presentation stays deliberately plain. The well is a dark rectangle, the four colours are bright and easy to tell apart, and a score sits off to the side. Nothing flashes for attention and there is no tutorial overlay explaining the rules. A first-time visitor is expected to drop a piece, watch it dissolve, and work out the colour-bridging rule from what happens on screen, which usually takes about one game. The restraint suits the toy: the physics is the spectacle, so the interface gets out of its way.

The sand does the work

This single rule change rewires the whole game. In classic Tetris, a row is binary: either every cell is full or the line stays. The player optimises for flat, tidy stacks. Sandtris punishes tidiness. Because every landed piece becomes fluid, a careless drop sends a red grain skittering into a blue region, poisoning a clear the player had been patiently assembling.

Clearing is dramatic rather than instant. When a same-colour stream finally bridges both walls, that entire connected mass dissolves at once, and everything resting above it slumps downward to refill the space. One good clear can trigger a cascade, which can trigger another. A board that looked lost resolves into calm in a second or two. It is oddly satisfying to watch.

The effect is that the player thinks less like an architect and more like someone managing a landslide. Colour matters more than shape. A long vertical piece is not a tool for digging a tidy column, it is a bucket of sand waiting to go wherever the terrain tilts.

A short example shows the difference. Drop a red square piece cleanly against the left wall and it holds its shape only for a frame before relaxing into a low red mound. Add a second red piece beside it and the two mounds merge into one slope. Keep feeding red toward the right and the slope lengthens until a single ribbon of red grains finally touches the far wall. That is the moment the board rewards: the ribbon flashes and drains away, and whatever sat on top drops into the vacancy.

Why the physics feels fair

Granular simulation can look unpredictable, but the behaviour here is deterministic. Each grain moves one cell per tick, checking the space below and then the diagonals, the same cellular-automaton logic that has driven falling-sand toys for two decades. Nothing teleports. With a little practice the player can predict roughly where a spilled piece will settle, which is what turns luck into skill.

That determinism is why the game reads as fair rather than chaotic. A loss is almost always traceable to a specific bad drop, not to a random grain doing something impossible. The physics is strict enough to learn and loose enough to keep surprising, which is a narrow band to hit and a large part of why the toy holds attention past the first game.

A genre older than it looks

Sandtris did not invent falling sand. It belongs to a lineage of what are literally called falling-sand games, a genre in which simulated particles drop and interact with one another according to simple physical and chemical rules. The best-known example is The Powder Toy, documented on Wikipedia as a sandbox originally created by Stanislaw K. Skowronek and dating to 2008, where players paint with hundreds of materials and watch them burn, freeze, and dissolve.

Those sandbox toys are open-ended: there is no score, only a canvas of physics. Sandtris takes the same grain-by-grain simulation and bolts a win condition onto it. That is the clever part. The underlying engine is decades old and well understood, but pointing it at a competitive puzzle goal makes it feel new. The same hypnotic pull that keeps people watching grains settle on a toy like Sandpile is here harnessed into something you can lose.

The win condition is what converts a screensaver into a game. A pure falling-sand sandbox is pleasant but inert: nothing is at stake, so attention drifts after a minute. By insisting that only a wall-to-wall colour band clears, Sandtris gives every grain a purpose and every drop a consequence. The result keeps the meditative quality of watching sand move while adding the small, steady tension of a board that is always one bad piece away from trouble.

From Setris to a small forest of clones

The specific idea of Tetris pieces that turn to sand went viral through one game: Setris, by the developer mslivo. It reached the front page of Hacker News in May 2023, collecting more than 850 points and a long comment thread. That discussion is where much of the mechanic was first picked apart in public, including a memorable exchange about whether the sand appeared to fall up or down (the developer explained it accumulates one particle per tick as pieces cascade from above).

The Hacker News thread also previewed the game's biggest problem, and it was not technical. Commenters warned that anything sounding like Tetris invites legal attention, floating alternative names such as Sandtris precisely to stay clear of it. That caution proved well founded: the original Setris listing on itch.io was later suspended following a trademark claim, as its itch.io page now shows.

The takedown did not kill the idea. It scattered it. Because the concept is simple to describe and the underlying physics is public knowledge, dozens of versions appeared across app stores and game portals under names like Sandtrix, Sandtris, and Sand Tetris. Sandtris on the open web is one of these descendants, and one of the more faithful.

Why so many versions exist

A viral mechanic with a contested name is a recipe for proliferation. No single company owns falling sand, the colour-matching rule is easy to reimplement, and the whole thing runs comfortably in a web page. Each clone makes small choices: how fast sand flows, how many colours, whether there is a leaderboard. The result is a small ecosystem of near-identical games, which is itself a very internet kind of outcome.

The spread was helped along by short video. Clips of the sand collapsing are tailor-made for social feeds, where a satisfying cascade reads instantly without explanation, and the game resurfaced repeatedly under different names as a result. That churn is why a search for the concept today returns app-store entries, portal listings, and standalone pages that all play almost identically. The open-web version at sandtris.com is simply the one that asks the least of a visitor: no store page, no install prompt, just the game.

Built in the browser with p5.js

What distinguishes the version at sandtris.com is that it runs instantly, with nothing to install. Its own credit line reads that it was made by Franco Miranda, whose site sits at francomiranda.com, using p5.js and inspired by Setris. The page also carries the sensible disclaimer that it is not affiliated with Tetris.

The choice of tool is telling. p5.js, maintained by the Processing Foundation, describes itself on p5js.org as a friendly tool for learning to code and make art. It is the library of countless classroom sketches and generative-art experiments, not the heavyweight engine one might expect for real-time particle physics. Running a full grain simulation at a playable frame rate in that environment is a quiet technical flex.

The browser build adds the trappings that keep people coming back. There are toggles for music and sound effects, a pause key, a game-over screen, score submission, and a weekly leaderboard that resets the competition on a schedule. Mobile play is supported too, so the game is not tied to a keyboard.

The weekly reset is a small but effective design decision. A permanent all-time leaderboard would be hopeless to crack for anyone arriving late, since the top scores calcify. Resetting every week keeps the top of the board within reach, gives a casual player a reason to return on a Monday, and turns a solitary toy into a low-stakes weekly contest without demanding anything like a subscription or a profile.

How to actually play it

The controls are the ones muscle memory already knows. The left and right arrows move the active piece, the up arrow rotates it, and the down arrow drops it faster. Holding shift or control nudges the piece across quickly. The letter P pauses. On a phone, touch controls stand in for the keys.

Strategy, though, is nothing like Tetris. The winning habit is to commit to colours by region: build a wall of one colour against the left edge and reach steadily toward the right, rather than scattering shades evenly. Because sand flows, the player should drop pieces where their grains will slide into the colour they belong to, not simply where a shape happens to fit. Rotating a piece before it lands matters less than aiming its eventual spill.

Mistakes compound. A single misplaced piece can bury a nearly complete bridge under the wrong colour, and unlike a clean row there is no quick way to dig it out. The grains have to be covered, cleared around, or outlasted. That fragility is exactly what makes a successful cascade feel earned.

The pace escalates in the familiar way, pieces arriving faster as the game goes on, so early composure matters. A good run usually comes from keeping the sand low and the colours sorted while there is still room to think, then cashing in several bridges in quick succession when the well starts to crowd. Hoarding a near-complete colour for a big chain is tempting and often how a promising board ends: one wrong shade on top, and the whole plan is buried before it pays out.

Why it belongs on a list of boring websites

Sandtris is boring in the specific, admiring sense this blog cares about. It does one thing. It opens to a game and nothing else, with no feed, no onboarding carousel, and no reason to create an account. A person arrives, plays for four minutes or forty, and leaves. The entire experience is contained in a single page that could sit open in a background tab for a year.

It also rewards the kind of idle, repetitive attention that the best single-purpose sites specialise in. There is no narrative and no ending, only a loop that gets a little more tense each time the well fills. The pleasure is in the material itself: watching coloured grains pour, pile, and suddenly vanish in a satisfying collapse. That is a small, complete idea executed cleanly, which is the whole point.

There is a quiet lesson in how it was made, too. The same concept exists as paid app-store downloads and as listings wrapped in portal chrome, yet the version worth bookmarking is the plain one that loads in a tab and starts. Stripping away the store page and the install step is not a limitation here, it is the feature. A single page that does one thing well, with nothing between the visitor and the game, is exactly the sort of modest craft this blog keeps a shelf for.

For anyone who keeps a mental shelf of oddly compelling web toys next to the hub at Boring Websites, Sandtris earns a spot. It is proof that a twenty-year-old physics trick and a forty-year-old puzzle shape still have a surprise or two left when someone bothers to combine them in a browser tab.

FAQ

Is Sandtris the same as Tetris?

No. It borrows the falling-tetromino shapes, but the clearing rule is completely different. Rows never clear by being filled. Pieces turn into sand on landing, and a connected band of a single colour that touches both walls is what disappears. The site at sandtris.com explicitly notes it is not affiliated with Tetris.

Who made Sandtris, and is it free?

The web version was built by Franco Miranda using the p5.js library, inspired by mslivo's Setris. It is free to play in a browser with no account or download, and includes a weekly leaderboard for anyone who wants to compete.

Do I need to install anything or sign up?

No. Sandtris runs entirely in the browser on desktop and mobile. There is no installer, no sign-up, and no app required. Opening the page is enough to start playing, which is part of why it fits the single-purpose spirit of the sites catalogued at Boring Websites.

What is the trick to clearing lines?

Think in colours and terrain, not shapes. Commit each colour to a region and build a continuous bridge of it from one wall to the other, dropping pieces so their grains spill toward the matching colour. Because the sand flows, aiming where a piece will settle matters more than fitting it neatly into a gap.