Slither.io is free to download, offering players a simple and entertaining gaming experience without an initial purchase. However, the game does contain in-app purchases that allow players to enhance their gameplay experience, such as removing ads or acquiring cosmetic items to personalize their slither.

Advertisements are a part of the free version of Slither.io, displayed during or between gameplay sessions. Players can opt to remove these ads through a one-time in-app purchase, contributing to a smoother gaming experience. Although the core gameplay is free, these optional purchases and ad experiences are important to consider for players looking for an uninterrupted and personalized gaming session.

Installation on iOS Devices: To install Slither.io on your iOS device, make sure your device is running iOS 8.0 or later. Open the App Store on your iPhone or iPad, and type 'Slither.io' into the search bar. Locate the game in the search results, and tap on the 'Get' button followed by 'Install' to begin downloading. You may be required to enter your Apple ID password or use Face/Touch ID for confirmation. Slither.io requests permissions for notifications, which you can manage in your device settings if desired.

Installation on Android Devices: For Android devices, ensure you have at least Android 2.3 or higher. Open the Google Play Store, and search for 'Slither.io' using the search function. Find the game in the list, and tap the 'Install' button. You'll need to accept permissions, including network access for online gameplay. Once installed, you can find Slither.io on your home screen or in your app drawer, ready to play.

Step 1: Launch the game after installation. You'll be greeted by a simple main menu with options to start the game, access settings, and customize your snake's appearance.

Step 2: Before playing, spend a moment in the customization menu. Here, you can change the skin of your snake, selecting from a variety of colorful patterns available from the get-go.

Step 3: Tap on 'Play' to begin. Your snake will appear in a vast open arena full of other players. The goal is to consume glowing pellets while avoiding other snakes to grow in size.

Step 4: Navigate your snake using touch controls or mouse input. Direct your snake's head towards pellets by swiping or moving the cursor. Avoid crashing into other snakes, as doing so will end your game.

Step 5: Watch for opportunities to cut off other snakes. If they collide with you, they'll turn into a series of pellets ripe for consuming, which will significantly increase the size of your snake.

Tip 1: Always stay near larger snakes. Their movements can lead to massive pellet piles if they collide with another snake. Capitalizing on their downfall by swooping in quickly can give your snake a considerable size boost.

Tip 2: Use the speed boost wisely. It allows your snake to quickly maneuver around obstacles or other snakes, but be cautious; it shortens your snake slightly with each use. Utilize speed strategically for cutting off opponents when necessary.

Tip 3: Stay alert and constantly adapt your tactics. The game is dynamic, with numerous players in the arena simultaneously. By keeping a keen eye on the surroundings, you'll be better equipped to react promptly to threats and seize opportunities that arise.