Pipe Rush

Pipe Rush is a pipe-laying puzzle. There is a source somewhere on the left of the board, a queue of pipe pieces you cannot reorder, and a countdown. When the countdown ends the water starts moving, and from then on you are laying pipe in front of a thing that is already coming. Your score is the number of tiles the water gets through.

How to play

Click or tap any empty square to lay the piece at the front of the queue there. You do not get to choose which piece — only where it goes, which is the whole game. The four pieces behind it are shown so you can plan two or three moves out. On a keyboard, tab to the board once, move with the arrow keys and press Enter or Space to lay.

The clock does not start until you lay your first piece, so there is no rush to read this. Once it does, you have fifteen seconds on level one before the water starts. Pressing Release starts it early, which is worth doing when you are happy with what you have built.

Winning a level, and losing a run

Each level asks for a number of tiles — eight on level one, ten on level two, rising by two a level up to a cap of forty. The water runs until it has nowhere left to go: the edge of the board, a bare square, a wall, a pipe that does not open towards it, or a pipe it has already been through.

That stop is the level. If the water has filled at least the number of tiles asked for, the level is cleared and the next one starts. If it has not, the run is over. So the two situations are the same event and it is your distance that separates them — which means a run that is going badly is still worth building for, and a run that is going well is worth pushing past the target, because every tile counts towards the score you carry to the next level.

Laying over a pipe you have already put down

You may lay a piece on top of one the water has not reached yet. This is what makes a bad run of pieces survivable, so it is not free: it costs two seconds off whichever clock is running. Before the water starts that is two seconds off the countdown; after it starts it is two seconds off the wait for the next tile, which usually means the water moves one square sooner than it would have.

The cost never stacks up into more than one square of movement, however much of the clock was left. A piece the water is already in, or has been through, cannot be replaced at all.

The pieces

There are seven. A straight pipe comes in two orientations and makes up two fifths of the queue between them; the four elbows are the rest of it, at about one in seven each. The crossover — the piece with all four ends open — is the rare one, at one draw in fifteen, and it is the only piece the water may pass through twice: once on each axis. A loop that comes back through a crossover it has already used is the best two tiles in the game, and threading one is the thing worth learning.

From level two onward, a growing number of squares are blocked, up to seven. They are never placed directly in front of the source, so no board is lost before you have laid anything.

How the difficulty moves

Three things change as you go up, and they stop at different points. The countdown shortens by a second a level and stops at five, which it reaches on level eleven. The water speeds up from one and a half seconds a tile and stops at just under half a second, which it reaches on level thirteen. The target keeps rising until level seventeen, when it hits forty. That is forty of the fifty-five squares you actually have once the seven walls and the source are in, which is why it is capped there rather than going on climbing into a number the board cannot hold.

Every board comes from a seed

The source, the walls and the entire queue of pieces are generated from the short seed shown above the board, and the same seed always produces exactly the same game — the same source in the same square, the same walls, the same pieces in the same order, on every level. The seed lives in the part of the address after the #, which browsers never send to a server, so Copy link sends someone the exact game you played rather than a description of it.

There is no leaderboard and no account. Two people on the same seed are laying the same pieces on the same board, and the only thing that differs is what they did with them.