Slither.io

Gameplay

The objective of the game is to control and move a snake (or a worm to most players) around a colored area, eat pellets to gain mass, defeat and consume other players to grow the biggest and longest in the game. If the player's snake's head collides into a part of another snake, the player loses the game and must start over. The defeated avatar's body turns into bright, shining pellets for other players to consume. These pellets that remain from "death" of an avatar will correspond to the color of the avatar itself, and are both brighter and bigger than normal pellets.

Pellets also spawn from other snake avatars. By either pressing the space bar or clicking on the mouse or trackpad, the player can activate "boost mode", which causes the avatar to speed up. When a player uses "boost mode", the snake loses some mass, causing the snake's size to shrink slightly, with the mass that is lost from the boost appearing as a line of dots where the boost was used. This feature is useful to outmaneuver and defeat opponents. Another strategy that players use to defeat opponents is coiling around them in a loop until the opponent, trapped in the loop, crash into the player.

There is a border that confines avatars within the circular game board. If a snake hits the border, the player automatically dies without turning into the aforementioned pellets. A good strategy to defeat and consume enemies is by coiling and thereby trapping them within the player's snake, leading to the inevitable "death" of the opponents. According to the app description in the App Store, the player with the biggest snake at the end of the day gets to send a "victory message" to the world.

Skins

There are 12 default skins, each one a different solid color, which are randomly chosen when the player joins the server. Players can choose to customize their snake's appearances using custom skins with unique designs including different countries' flags, as well as skins with motifs and colors representing well-known YouTubers, such as Jacksepticeye, Jelly and PewDiePie. In order to unlock custom skins in browser mode, players must share the game on Twitter or Facebook using the external links found on the website. By June 2016, the ability to add skins was also added to the iOS and Android versions. Mobile versions also allow players to play offline against the computer using an artificial intelligence mode.

Protocol

The game uses WebSockets to communicate with the server, a low-latency protocol codified in the HTML5 standard and supported by all major browsers.

Development

According to game creator Steven Howse, the idea for the game came after he had financial problems. As a result of these financial issues, he had to move from Minneapolis to Michigan, where he realized the popularity of Agar.io. He had fostered a longstanding will to create an online multiplayer game, but the only option for the development at the time was in Adobe Flash, and he gave up the idea for a while, not wanting to use this method. The game was created when he realized that WebSockets were sufficient and stable to perform an HTML game, similar to that used in other games, such as Agar.io itself. The most difficult part of the development was in making each server stable enough to handle 600 players at a time. Howse struggled to find space on servers with enough space in regions where there was more demand and tried to avoid cloud services like Amazon Web Services, owing to the high cost that these services would incur based on the amount of bandwidth used.

After six months of development, Slither.io was released for browsers and iOS on March 25, 2016, with servers supporting up to 500 players. Two days after the iOS/browser versions' release, an Android version was made available by Lowtech Studios. The only way Howse could make revenue was to display advertising in the app after the player's snake died; this option could be removed for US$3.99. He chose not to sell virtual currency or power-ups so that those who paid would not have an advantage over players who didn't. As there was no money to advertise for the game, the only way to advertise was the various let's plays by players on YouTube, including PewDiePie, who had more than 47 million followers at the time.

In the weeks following the release, Howse worked on updates to stabilize the game and provide a better experience for players. In addition, he plans to add new features, such as a friendly mode; another mode that allows people to set up teams; and a way for the player to select the server he or she wants to play on. Howse said that two major gaming companies had approached him to buy Slither.io. He considered the idea, since his felt that it was stressful to maintain the game.

Reception

Slither.io reached the top of the App Store sales charts in the free software category in several regions, including the United States and the United Kingdom.

Patricia Hernandez of Kotaku said that the game's low barriers to entry and similarity to Agar.io explained Slither.io's popularity. She noted the game's fast pace. Boing Boing compared the game's core mechanic to that of the 2009 game Osmos. Brandt Ran, writing for Business Insider, said that "despite running into some technical hiccups—the game can lag heavily at times—I doubt Slither.io will be leaving my home screen anytime soon." Harry Slater, writing for Pocket Gamer, defined the game as "interesting"; the gameplay as a "compulsive experience"; and the structure as simple and similar to Agar.io, although it did not have a large replay value. TechCrunch's Felicia Williams praised the designs, getting "pleasantly surprised" with the variety of skins for customization. Lian Amaris of Gamezebo found the game to be "far more interesting than Agar.io" because it involved "an ever-growing languid body rather than just a flat circle," and praised "the dark environment with neon worms," which gave the game a "retro arcade feel." Amaris also compared the concept of Slither.io to that of Agar.io and stated that Slither.io was reminiscent of the classic arcade game Snake.

Shortly after the release of the mobile versions, the game was in first place in the ranking of games of the App Store. Despite Slither.io's popularity, it received mixed reviews. Scottie Rowland of Android Guys praised the gameplay and graphics, however criticized the ads that pop up on the screen after the end of the game, calling them "extremely annoying" and finding the payment to remove them "a bit pricey."

Popularity

By July 2016, the browser version's website was ranked by Alexa as the 250th most visited site worldwide, but then experienced a decline in popularity, dropping below 1,000 by October 2016 before remaining mostly constant at approximately 1,700 by January 2017. By that same period, the game had already been downloaded more than 68 million times in mobile applications and played more than 67 million times in browsers, generating a daily income of US$100,000 for Howse.