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Slither.io is a more interesting game than it may seem at first. In this post I discuss what is good on slither.io in the point of view of game design, what is wrong and how I would change it according to my view for make a better game.

Alberto Espinal, Blogger

June 2, 2016

19 Min Read


  • YOU CAN ALSO READ THIS POST ON: http://unreal-dreams.com/en/slither-io-game-design/





The gamers, especially those of PC, tend to be pedantic with videogames, and I say this in the bad sense of the word. The "PC master race" and in general the "pro gamers" we usually believe that we have the only one power of the truth, that is only one and one who disagrees is often punished with the criticism and the appearance of the blessed "internet trolls".

A game can only be or very good or very bad for this people, there is no middle point. A curious thing when Steam votes shows that most games have a "mostly positive", the average is neither very good nor very bad. When a video game is very popular and many people plays, even those that does not usually play video games, the game almost seems to automatically become a bad game. If it is a very popular game, it is a bad game... and people play it massively because they are half retard. This happens with League of Legends and even with Minecraft... Who is capable of giving me argued reasons for why they are bad games. Slither.IO has also become very popular and there are many people who consider it a bad game without giving any argument.

Do I want to say that Slither.io is an equivalent quality game to League of Legends or Minecraft? No, nor much less, I can't even say that Slither.io can be considered a good game. I just say that Slither.io has not become popular because yes. Developers have been able to deploy some really good game mechanics, some of them quite underused in the world of videogames, to create a simple and addictive game. Slither.IO is a game wich we can learn many things as game designers.


So much so that I've decided to make this article divided into three parts, the first part, divided into three points also, I will analyze what makes slither.io an interesting game. In the second part I will analyze mistakes that makes slither.io not a good game so much, but a game with excellent ideas. In the third part I will try to provide some design ideas that could turn a decent free game into something more serious, full and complex.

Let's begin to find out what Slither.io can teach us about video game design:



The gameplay of Slither.io is very simple: an online game in which several players face each other in an all against all, the player controls a worm that grows eating light balls, these balls are randomly around the map and above all are produced by 'death' of another worm. Size means just that, a change of size... and climb on the leaderboard of the room in which you are playing. Worms "die" when his head hitting the body of another worm, independent of the size of both, there is only an exception, when both worms are hit with their heads, in which case it wins the larger. There are two speeds, if we go quick, we will gradually lose size and leaving a trail of little light balls.

The rules are so simple that leave very important relative freedom to the player, allowing to decide himself how to play and invent his own techniques to defeat other worms and grow. With this simple mechanics, we learn to play in a very short time, so almost anyone can play. Is a browser game and load is very quick, also is in mobile, so potential audience of Slither.io is huge.

Simple ideas tend to be the most successful, because these ideas are assimilated them faster and they reach a greater number of people, much people can play of this game because does not need to have experience in other games. There are those who consider this something negative, because makes the game like a "casual" games and this is something that seems to offend the sensibilities of the "pro" player. As i already said at the beginning, the "pro" player is quite prickly... some guys that spend their lives playing games and they feel that they are saving the world, when the only thing they do is to limit to the wonderful world of videogames with his reduced reactionary vision .

This article is aimed primarily at developers of videogames. A videogame developer must also be a player, but not all players can be developers. The game designer must have an open mind, we have to acquire knowledge of everything and of course play a lot, because we will take playing most of our practical knowledge. We cannot isolate ourselves in our world and think only about the game that we want to do, we also have to think on our audience, we must never forget the player because in the end he will be who play our game. Of course, we can make super complex games and only for expert players, if that is our decision, but even when we want to make a hardcore game, we must be clear about the game that we want to do, it seems obvious, but in light of the large number of games that fail because their mechanics or gameplay are not well defined , it seems clear that it is necessary to remember this.

We must never forget that the player must understand our game and this is that makes it great slither.io in that sense. In just a few minutes we know what we are playing, without a tutorial, to guide or to wiki. I said "great" talking about Slither.io with awareness of the words I am using, because the same thing happens when we play classics like Super Mario or Tetris, the simplicity to understand the mechanics of the game is one of the hallmarks of what make great to these games. If besides simple, the idea is original and unique, we have then taken with one of the keys to success.



Make no mistake, the creation is a constant copy what has already been done before, we copy what we like, we copy what we've learned and even we copy us to ourselves. Slither.io is a game that don´t makes innovations in a radical sense of the word, they pick up from here and there to create a concept that looks like other things we've seen before but adding a original twist.


First the obvious, it is clear that Slither.io follows the footsteps of Agar.io and therefore is inspired by games like Osmos or the first stage of Spore. But Agar.io was a game too predictable, the idea of a multiplayer game everyone against everyone focused as a wild struggle for survival was good, but Agar.io only scratched at the surface, in the end the big one just almost always eating little, it is unfair, too frustrating and too slow.

Snake. Classic game for Nokia mobiles


But Slither.io also takes references from other sources that give the detail that make different to the game, mainly has playable references of the typical Nokia mobile Snake classic game, adding the detail that we don't die with ourselves, but when colliding with others. Basically applies to the world of the serpent the competitive multiplayer concept of Agar.io and the survival of Osmos, Spore, or mostly Flow, since the Thatgamecompany game promotes the idea that the small can defeat the large, besides that growth in worm appearance is closest to Flow that to the growth of exponential size of Osmos or Spore.


Copy is an art, if done well, copying in video games is not plagiarizing the gameplay of another game by changing the visual style, but refers more to take elements borrowed from other games and apply them to our own project or simply adding our own playable focus. Osmos, Spore and Flow share many elements in common, but we cannot deny that three games are quite different and are perfectly differentiated from the other both in appearance and gameplay, therefore, are unique games and are regarded as masterpieces by great part of gamers.




But not only by use of two biggest rules when designing a game, is Slither.io a interesting game. The small details are those that in the end make the difference.

  • Competitiveness: Slither.io would be nothing without competitiveness, directamente couldn't exist as game, because it lacks artificial intelligence. But in fact competitiveness is one of the big tricks that dazzles to the gamer. The human being is competitive by instinct. In fact, millennia ago we were hunters fighting with our own lives by getting food. We are thrilled to see our name on the list of largest worms in the room in that we are playing. There is no prize and be the largest wrom is not even a symbolic victory, even the smallest worm could defeat us. But we are made to compete and this game knows how to engage us, apparently is not difficult to be the biggest and therefore encourage us to try again and again, to die trying again and again, and try again.

  • David and Goliath: something that surprises me about Slither.io is that be large it does guarantee anything. It all depends on our ability and anytime a small worm can defeat us. That's something that makes big this game, usually whe we play a game during a long time make us to have best stats, unlockable weapons, more life, more level... In Slither.io yes, we can be bigger, that means nothing, rather becomes a problem already makes us more "tasty" and more players will try to kill us.

  • Chaos: a moment in that Slither.io becomes a game frenzy is when one of the large worms is defeated, then all the near worms around try to devour their remains, they press on with speed turbo and it makes harder to control the movements, often occurs a reaction chain in that the many of the worms that make it is happy with a quick growth may end up defeated by the greed. In those moments we can be on top for a few seconds and in the abyss then, or be the little worm was going through there and become one of the largest. Those moments are make them great to a competitive game such as this, when shown the ability of each person, regardless of their size.



The simplicity of Slither.io and their ability to take from here and there are the basis of the success of the vast majority of games that have marked history in this industry. And despite all, Slither.io is not a perfect game, not even would consider it a good game, already it has serious mistakes. There are very basic things that Slither.io does bad, but as we have seen, it has basic elements for make of it a entertaining and even addictive game.

I want to analyze what's wrong with slither.io and what would I do to, from my point of view as a designer, to make it better. But let's start by analyzing what's wrong in slither.io:

It is a browser game: this in principle is not a bad thing, in fact for many people it can make it more accessible, is no longer necessary to download or install anything, so only you access to the web and play, neither has long loads that it is one of the inappropriate things of browser games. But in my opinion, be a browser game creates a problem, the player tends to value it as a fleeting hobby, something you play awhile and one thing from another, so it is harder to make loyal to the player.

  • Art: the game lacks of an art minimally interesting, at least avoids the memes of agar.io and it has lighting effects, but neither stands out in its artistic section, is simple, no more. The art of slither.io has nothing to tell about the game, it's there because somehow it has to be visually represented.

  • It has no sound or music: This gives an unfinished appearance. The sound and music is really important for promote the inmersion.

  • Controls: a game like this, in wich losing is a fundamental part of the gameplay, controls must be run to perfection, the player should never have the feeling of lost because of the controls, but by an own error or a success of the adversary. In Slither.io controls work in a very inaccurate way, on the one hand the twist is too broad, so sometimes are the own controls that prevent dodge an opponent. On the other hand, the delay between mouse movement and its consequent reaction in our avatar is too high, this depends on the server lag and sometimes becomes desperate.

  • Lag: to the same happens in agar.io it is usual that lag makes game completely unplayable, it is something that depends on the server in you have the luck (or misfortune) of go on, it is a nuisance, because in principle we can not choose Server and it changes in each new game.

  • Bugs: I found several errors, as it is eternally charged when to try to start s new game or the new game screen appears when I press the "play" button  if I give before of have finished the "fade" effect.

These problems surely are the result of a hasty development, it is obviously not a game made with the intention of being relevant, but only made for entertain and perhaps with economic interests, I don't know, the thing is that development feels abrupt and little worked. Even so, it's not a bad game, as I already argued, has positive things that make it a very interesting game.



We have talked already about the good and bad things that have Slither.io, is the moment to talk about what I would do to improve it. You must keep in mind that as with any review, this is a subjective analysis. Can I take certain design decisions that another Designer wouldn't take, and as with any game design, is not something scientific, there is no magic formula for success.

This is just the previous work to the production of the game, they are only ideas, and as happens throughout any development of a videogame, there are differences between what one has in the head and the final result. The design alters for several reasons, the first is that throughout development ideas are discarded, others are generating and some change. On the other hand, in a teamwork, as is often make a game, usually arise variations of the original idea due to the dynamics of the teamwork.

In conclusion, all the ideas I propose here arise from my own experiences as a player and as a designer. They are personal decisions and some may be more dicutibles and other less, I do not intend to say the absolute truth over whether my idea of game is better or not, I only go to discuss my personal vision.

  • GENERAL IDEAS: my idea would be to make of Slither.io a more serious and competitive game. One of the reasons why Slither.io is attractive is because it is very competitive, achieve the first place is addictive, but once a game ends there is no any persistence. I think that the game could be much improved by adding elements typical of the multiplayer online games, as the user's profile, customizations, table of global classification or social elements and team play. I as a designer would also encourage the more aggressive and frenetic side of the game, with faster gameplay and a much more detailed and impressive appearance.

  • COMPETITION: for enhance the competitive element I would add persistence to the game. It seems to me that it would improve affiliation and interest of the gamer with the existence of a profile where the gamer could see their scores and compare them with others players, with several rankings as the best personal score, global scores... It would also be interesting to add the possibility to repeat and share the best moments. It could also add a competitive mode like style league of legends, with qualifying league in which the gamers would play against anothers of a similar level to promote in a global ranking.

  • GAME MODES: alongside the classic game mode that could be called "Arena" in which players enter a server with other players at random, it could implement other modes of game, as the mode of ranked competitive, in which all players start at the same time and it can only be left one. It would also be interesting to implement team play modes, the basic two would be the showdown by teams, both with friend damage and without it.

  • SOCIAL ELEMENTS: Play with friends should be as simple as creating a room with friends and searching a game, the friends could play in all game modes and even create competitive teams . An advantage of this game with respect to other games multiplayer is the large number of players who can be in the same game. In the original Slither.io the rooms are at least of 500 people, would be interesting to see the youtubers playing with hundreds of subscribers, or a complete class of a school playing the same game, or even to all players of a lan party. The playable possibilities at social level of so many gamers playing together are enormous. On the other hand I miss a chat during the game, many times I have wanted to discuss a play or a funny name. In theory, the developers have implemented a chat in one of the versions of the game, but I have not seen it or it hasn't given me the feeling that there is one.

  • GAMEPLAY: regarding the playable appearance there are a couple of things that I would change, on the one hand I would eliminate the fact that is lost size when the worm go fast, since when it reach certain size this loss is no longer relevant and works more as a psychological resource than as something real. I think to removing this, the player would do greater use of speed, making the game more frantic and complicated, since by increasing the speed, the reflexes become more important and it's easier that any players caught off guard  to anothers. On the other hand, I would improve controls, making them more accurate and agile and reducing the response time to the minimum possible.

  • ART: art is something essential in a game and it can reinforce the symbolic aspect of the game. As I seek the aggressiveness and competitiveness in the game seems to me more appropriate give an equally aggressive look to the art, giving more plausibility to the designs, with designs inspired by the wildlife, full of spikes, hooks, teeth sharp... along with a more stylized overall appearance. In terms of color and the general atmosphere, I think that games like Flow and Osmos give us primary keys, with such designs like of life seen through the microscope, with few colors, bright lighting with flashy lighting effects and the feeling that the game happens under the water, with some of blur.

  • SOUND AND MUSIC: the sound would be fundamental for the immersion of the player, with strong and forceful effects, with certain echo, as if we listen sounds under the water. The music would be scarce and adaptive, focusing above all on intensify the moments of tension.

  • CUSTOMIZATION: since the "worms" are growing by separate fragments, would be relatively easy to customize them, so each player could join the fragments that he previously unlock as a puzzle, creating a "worm" fully customized and according to their likes.

Simple sketch that shows a possible artistic design, with a more aggressive aspect worm and a aquatic environment

The ideas that I shared are not especially innovative or different, it is not necessary, the original game itself already offers the original and amusing playable elements, but if we combine these ideas with a good well-worked design, the interesting ideas can emerge as a full product. Some of the best ideas in the history of video games emerged as well. Without go further, Notch, the creator of Minecraft took good ideas of a game named Infiniminer and he polished them to create a practically perfect game. After all, a game designer must not only have original ideas, but also he want to know how to discover good hidden ideas in some hidden gems and turn them into good games. We have not only to be good artists, that is, have good ideas, almost more importantly be good craftsmen and turn good ideas into good well finished products.


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