Snake

How to play: the snake never stops. It advances one cell at a time in whatever direction it is facing, and all you control is when it turns. Steer with the arrow keys, with W/A/S/D, by swiping across the board, or with the four buttons underneath it. Every apple you eat adds one segment to your tail and 10 points to your score. The run ends the instant the head leaves the 20×20 grid or enters a cell your own body is already in — there are no lives and nothing to shoot.

The turn you cannot make. A snake may never double back into its own neck, so pressing the direction you came from does nothing at all. What is easy to miss is that this also applies to turns you have queued: the game buffers up to two presses so a corner taken quickly is not lost, and each one is judged against the last buffered turn rather than against the direction on screen. Press down and then up while heading right and the second press is discarded, because by the time it would be applied the snake is heading down and up is a reversal. Press up and then left and both are kept — that is a genuine U-turn, spread over two moves.

Chasing your own tail is legal. The tail vacates a cell on the same move the head enters one, so steering into the square your last segment is leaving is a clean pass, not a crash. The exception is the move you eat on: an apple keeps the tail where it is for one tick, and that is exactly the tick on which the same manoeuvre kills you. Long snakes die in that gap more often than they die on walls.

Speed rises with length, in ten steps. You start at speed 1, moving one cell every 150 milliseconds — about 6.7 cells a second, or three seconds to cross the board end to end. Every three apples takes 9 milliseconds off the tick, so speed 2 arrives at 3 apples, speed 5 at 12, and speed 10 at 27 apples and a score of 270. That top speed is 69 milliseconds a cell — 14.5 cells a second, and a board crossing in 1.38 seconds — and the game does not accelerate past it. Everything after apple 27 gets harder purely because the snake is longer, which is the part you can do something about.

Strategy that actually helps. Beginners chase the apple in a straight line and die of a tail they stopped thinking about. Two habits fix most of that. First, keep to the edges and treat the middle as somewhere you pass through rather than live in — a snake coiled around the centre has cut the board in half and has nowhere to put the next twenty segments. Second, before you commit to an apple, look at where your own tail will be by the time you get there, not where it is now: it moves as you do, so a wall of body that looks fatal is often gone by the time you arrive. Strong players effectively follow one long loop around the whole board, collecting apples that happen to fall on it and taking short detours for the ones that do not.

The theoretical ceiling. A perfect game fills all 400 cells. You start with 3 segments, so that is 397 apples and a final score of 3970. Nobody reaches it by playing well; it is reached, if at all, by following a fixed cycle that visits every cell in turn, which is a different activity from playing Snake. A human score in the high hundreds is a very good game on a board this size.

Snake is one of the oldest video games there is — the arcade cabinet Blockade ran the idea in 1976, and Nokia putting it on the 6110 in 1997 made it the first game most of the world carried in a pocket. This version runs entirely in your browser: your best score is kept in local storage on this device, nothing is uploaded, there are no accounts, and it keeps working with the network switched off.