How to play Fusegrid

Fusegrid

Two to four players share one walled arena of pillars and crates. You place a firecracker on the cell you are standing on, it fizzes for two seconds, and then it throws a cross of sparks that clears crates and catches anybody still in it, including you. The last player standing takes the round, and the first to two rounds takes the match. After forty-five seconds the arena starts closing in, one cell at a time, so a round always ends.

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The field

The arena is 13 cells by 13, walled all the way round, with a pillar at every other cell inside it. The pillars are what make the corridors, and nothing ever removes one.
The rest of the interior is crates, about 65 in every hundred open cells. A crate blocks you and it blocks sparks, and it is cleared by the first cross that reaches it.
Each player starts in a corner with the corner cell and one cell along each corridor left clear, so nobody begins beside a crate. The seed decides which corner each player gets. At two players the corners are diagonally opposite.
You walk one whole cell at a time, taking four tenths of a second to cross one. Turning is free: only a step costs you the wait. Steer with the arrow keys, with W, A, S and D, by swiping the arena, or with the pad on a phone.
Another player is a wall. You cannot walk through one and you cannot swap places with one.
A round opens with a three-second countdown, and nobody moves until it has run.

Your firecracker

Press the space bar, tap the arena, or hold the button on a phone to place a firecracker on the cell you are standing on. You start each round with one.
A firecracker fizzes for two seconds and then pops. Nothing can stop it once it is down, and nothing can move it.
The cell it is on blocks everybody else at once. You can stand on your own until you step off it, and then it blocks you too.
You can never have more firecrackers fizzing at once than you carry. You get one back the moment one of yours pops.

The cross

When a firecracker pops it throws four arms of sparks, north, east, south and west, one cell long to begin with.
An arm stops dead at a pillar. An arm clears a crate and stops there, so a cross never reaches past the first crate it meets.
Sparks stay for four tenths of a second. Anybody standing in them at the end of a tick is caught and is out for the rest of the round, and that includes whoever placed it.
Everyone caught on the same tick is caught together. Being caught by your own cross is the commonest way to go out, and it is nobody else's doing.
A firecracker reached by sparks pops on the same tick, and so does anything its own cross reaches. A chain goes off all at once rather than one after another.

The marks

Some crates hold a mark, and you can see which from the first tick: there is nothing hidden in this game.
A cleared crate leaves its mark lying on the cell. Walk over it to take it. A mark lying in sparks is burned.
A firecracker mark lets you have one more fizzing at once, up to four.
A cross mark makes your arms one cell longer, up to five.
A feet mark makes you faster, down to two tenths of a second a cell. There are four of each kind in the arena.
Taking a mark you are already at the ceiling for still takes it off the field, which is worth doing to deny it to somebody else.

The arena closes in

After forty-five seconds the walls start closing in. One cell of an inward spiral turns to a pillar every four tenths of a second, starting at the outside.
The next cell flashes for eight tenths of a second before it closes, so you always have warning.
Standing on a cell as it closes puts you out. Anything lying on it is gone, and a firecracker on it is removed without popping.
The spiral is 121 cells, so the arena is always gone by ninety-three seconds and the round always ends. Two players closed in on different ticks means the later one wins.

Worth knowing before you start

The first player to take two rounds wins the match, and a match is five rounds at the most. Level at the top is a draw.
The last player standing takes the round. If the last two are caught on the same tick the round belongs to nobody.
The server runs the arena and decides everything. Your step takes effect on the next tick, a tenth of a second, and the page draws you moving before the answer arrives so it feels immediate. It never draws a cross that has not happened.
Fusegrid needs a live connection. If your browser or network cannot open one the page says so rather than offering a game that cannot move.
Placing is the easy half and stepping away is the hard half. Count the cells out of the cross before you press, not after, and remember your own arms grow as you collect marks.
A player who resigns is out of the match. At two players the other one wins; at three or four the match goes on without them and they are placed last.
Every seat is live the whole time, so the site's move deadline of five minutes is only a dead man's switch: if nothing at all happens for that long the match is abandoned and nobody is rated. A player who leaves in the middle is covered by the bot, and forfeits their seat after being away for two whole rounds.
The bot plays at one of three strengths, drawn per match from the seed. All three look ahead to work out where the sparks will be and whether they can still reach somewhere safe; what separates them is how often they stop paying attention, and the weakest of them does it often.

The seed decides the crates, which of them hold marks, and which corner each player starts in, and nothing else: there are no dice here, so a round follows entirely from the arena it was dealt and the steering. It is published when the match ends, so the whole match can be replayed from the log and checked.

Fusegrid terms

A firecracker: What you place. It fizzes for two seconds on the cell you left it on, then throws a cross of sparks. You start with one and can carry up to four at once.
The fuse: The two seconds between placing a firecracker and its cross. Nothing stops it and nothing moves it.
The cross: The four arms of sparks a firecracker throws. One cell long to begin with, up to five, stopped by a pillar and stopped by the crate it clears.
Sparks: What the cross leaves on a cell for four tenths of a second. Anybody standing in them is caught.
A crate: A block you cannot walk through and sparks cannot pass. The first cross to reach one clears it, and some of them hold a mark.
A mark: What a cleared crate leaves lying. Walk over it to take it: one more firecracker, a longer cross, or faster feet.
A pillar: A block nothing removes. They stand at every other cell, and the closing turns cells into them.
Caught: What happens when sparks are on your cell at the end of a tick. You are out for the rest of the round.
Standing: Still in the round. The last player standing takes it.
The closing: The spiral of cells that turn to pillars after forty-five seconds, one every four tenths of a second, until the arena is gone.

Playing it here

Against a person or the bot. The bot needs no account and starts at once. To play a person, be rated and keep your games, you need an account: an email address and a password.
At your own pace. Every move has a deadline you both see, from one minute to a week. A game can take an evening or it can take a fortnight.
Nothing to buy and nothing to win. No stakes, no prizes, no boosts, no undo. The only thing on offer is a place on a leaderboard, and only if you want one.
Every game can be checked. Anything decided by chance comes from the game's seed, and the seed is published the moment the game ends, so any finished game can be replayed and verified by anyone. See fair play.