The Walls Can't Kill You: How to Get Good at Snake

Snake is the rare game where succeeding is the thing that eventually kills you. Every piece of food adds a segment, and every segment is one more square of the board you can no longer occupy. Your score and your obstacle course are the same number. Nothing else on the board is trying to stop you.

That last part is more literal here than you might expect, because on CerdikCerdik's version the edges wrap. Drive off the right-hand side and you reappear on the left at the same height, still moving. Off the top, back on at the bottom. The board is twenty by twenty, but topologically it is a loop in both directions — there is no corner to be pinned into and no wall to crash against.

If you grew up on the Nokia version, this quietly invalidates most of your instincts. In wall-killing Snake, the edges are the main danger and the received wisdom is to hug the perimeter carefully and treat the corners as traps. Here the perimeter is not dangerous at all, and there are no corners to speak of. The classic way of dying has simply been removed.

So what is left? You are. Self-collision is the only losing condition, which means every single death is one you built yourself, usually several moves before it happened. That is worth sitting with, because it changes what you should be paying attention to. You are not dodging hazards. You are managing a shape.

The first habit that follows is to travel in lanes. A snake laid out in long parallel rows leaves gaps that are predictable and wide enough to enter. A snake that has been scribbling around the middle of the board has carved it into pockets, and the moment you enter one with only a single exit, the game is decided — you just don't find out for another ten moves. Keep the body tidy and the board stays navigable even when the snake is very long.

The second is to follow your own tail when things get crowded. The tail is the safest thing on the board, because the square it currently occupies is about to be empty. Anywhere directly behind your tail is space that is opening up rather than closing down. On a packed board, tracking your tail is close to a guarantee that you have somewhere to go next.

The third is specific to the wrapping board, and it is the one most players miss for their first few games: the shortest route to the food may run off the edge of the screen. Food sitting two squares from the left border, while you are near the right border, is two squares away going right — not eighteen going left. Once you start seeing those routes, your average path length drops noticeably, which matters more than it sounds, because every wasted move is a move spent growing nothing while the board fills up.

Then there is the question of speed, and this is where most scores actually get decided. Easy steps the snake every 180 milliseconds, Medium every 120, and Hard every 75. Hard is roughly two and a half times the pace of Easy, but the difficulty does not scale by two and a half — it scales by much more, and the reason is not reflexes.

At 180ms you can see the food appear, work out a route, and execute it. At 75ms you cannot. There is no room to plan after the food appears, so the planning has to have happened already: you need a default shape you are maintaining and a rough policy for where you go next, so that when the food shows up you are adjusting a plan rather than making one. Players who move up to Hard and keep playing reactively watch their scores fall further than the speed difference alone can explain, and this is why. Hard does not take away your reaction time. It takes away your thinking time.

In principle the game is finishable. Four hundred squares, no walls to kill you, and a perfect player never loses — filling the board completes it. In practice the endgame requires plotting a path that visits every remaining square without sealing yourself off, which is a genuinely hard problem and the reason almost nobody gets close.

If any of this sounds familiar, it should: it is the same skill 2048 asks for, which we went through at cerdikcerdik.com/blog/2048-planning-ahead. Both games punish the move that looks best right now and reward the one that keeps your options open. Snake just makes the consequence more vivid, because in Snake your past decisions are sitting right there on the board in front of you.

Have a go at cerdikcerdik.com/games/snake. Start on Easy, get a feel for the wrap, and only move up once you are dying to your own body rather than to surprise.