Snake Game

The rules and numbers behind this Snake

The board is a 20 x 20 grid (300 px wide, 15 px per cell), and the snake advances exactly one cell every 120 milliseconds. Speed never changes: eating does not make the game faster, so the pace at the start is the pace at the end. Each piece of food is worth 10 points and adds one segment. A new game begins with a length-1 snake sitting near the middle of the board, motionless until you press the first arrow key. Hitting a wall or any part of your own body ends the run on the spot, and if you fill all 400 cells the game ends with a perfect score. Every figure below is derived from these settings.

Length always equals score / 10 + 1, so the highest possible score is 3990 points (399 pieces of food). The score counts food eaten and nothing else; surviving longer without eating earns nothing.

Getting a feel for the clock

At 120 ms per cell the snake covers roughly 8.33 cells per second. Travel times for a few distances:

If the food is 13 cells away by Manhattan distance (horizontal gap plus vertical gap), even the shortest route takes 1.56 seconds. Most of the game is planning a path that your own body does not wall off during that time.

Controls and input handling in detail

• Only one turn is applied per step. If you press several arrow keys inside the same 120 ms window, only the last valid direction is used for the next move.
• Reversing is ignored. While moving right, pressing left does nothing once the snake is longer than one segment. To make a U-turn you must first step up or down, then press left on the following step. Pressing “up, left” inside the same step will drop the left press.
• Moving into the cell the tail currently occupies counts as a crash. The head is compared with the whole body before the move, even if the tail would have left that cell at the same moment. Some Snake versions allow that move, so rules differ from game to game.
• Pause with the Space key or the button. Arrow keys and Space are captured by the game so the page does not scroll while you play. Switching to another browser tab also pauses the game automatically.
• Food appears on a random cell that the snake is not occupying (Math.random, which is fine for a game but not cryptographically secure).

Worked examples

Example 1: distance. With the head at (10, 10) and the food at (3, 16), the gap is 7 columns plus 6 rows = 13 cells, so the fastest possible arrival takes 13 x 0.12 s = 1.56 s. If your body sits on that route you have to detour, and the distance grows.

Example 2: a dead end made of your own body. Imagine a length-4 snake curled into a 2 x 2 square with the head facing the cell the tail is in. Because this version treats the tail cell as occupied, the head cannot enter it and the run ends immediately. Even a short snake can trap itself, so look two cells ahead before every turn.

Example 3: what a perfect game needs. To fill every cell you must eat 399 pieces of food, reaching length 400 and a score of 3,990. A 20 x 20 board has an even number of rows and columns, which means a Hamiltonian cycle exists: a closed loop that visits every cell exactly once. Following that loop forever would, in theory, never crash. It is not the fastest way to eat, though, so it takes much longer than an efficient but riskier run.

Practical tips and common mistakes

1. Do not hug the walls by habit. Along an edge one side is already blocked, which halves your options. While the snake is short, use the middle of the board.
2. Move in wide loops as you grow. Zig-zagging in tight spaces makes it easy to cross your own tail.
3. Take your time with corner food. A corner cell has only one or two approach paths, so secure your way back out before you go in.
4. Do not mash keys. Only one direction is read per step, so extra presses add nothing, and the last one may not be the one you meant.
5. On a phone, learn where the buttons are first. Find a grip where your thumb does not cover the board.

Limits and what is stored

• The best score lives only on the open page. Reloading or coming back later resets it to 0. Nothing is written to browser storage or sent to a server, and it is not shared between devices.
• There are no speed levels, obstacles or wall-wrapping modes. This is the plain baseline version.
• The game is driven by the browser’s frame callback, which stops in background tabs; that is why the game pauses when you switch away.

Using your result

Convert your score to a length (score / 10 + 1) and compare it with the share-of-board column above to see how much of the grid you can currently fill. If your runs keep ending at a similar length, the cause is usually the same kind of mistake at that stage, so replay the last few cells of the path before you died.

A short history of Snake

Steering a growing line to eat food goes back to late-1970s arcade games such as Blockade, and a version that shipped on Nokia phones in the late 1990s introduced it to a huge audience. Versions differ in speed changes, wall-wrapping and tail-cell collisions, so scores from different Snake games cannot be compared directly.

Frequently Asked Questions

More mini-games

Try the color sequence memory game for a memory challenge, Breakout for ball-and-paddle action, or the maze escape game for path-finding.