Geometry Dash is a 2013 side-scrolling rhythm platform video game developed by Swedish game developer Robert Topala and published by his company RobTop Games. It was released for iOS and Android in August 2013, Windows Phone in June 2014, and on Steam in December 2014. The player controls an icon and must navigate through levels while avoiding obstacles. Geometry Dash includes 26 developer-made levels: 22 are auto-scrolling, and 4 are platformer levels. Geometry Dash includes a level editor, enabling players to design custom levels, share them online, and play levels created by other users.

Topala released his first game, Bounce Ball Thingy, on Newgrounds in June 2010. As he continued to develop games, he quit his civil engineering course to pursue his career as a game developer, releasing a handful of games prior to Geometry Dash. He began development in early 2013, being inspired by other titles such as The Impossible Game and Super Meat Boy. He published Geometry Dash in August 2013 and it quickly gained popularity. Since its release, Geometry Dash has seen numerous updates that have added gameplay elements, levels, game modes, and features.

Geometry Dash has received mostly positive reviews from critics, highlighting the large variety of music, colorful visuals, and extremely difficult but rewarding gameplay. The level creation feature and the user-made levels it has spawned have been the subject of praise and has allowed Geometry Dash to gain a large and growing community.

A free version of the main game, Geometry Dash Lite, was released a month after the original. It removes certain official levels and icons, access to the majority of user-generated content, and the level editor. Three spin-off games accompany the main series: Geometry Dash Meltdown, Geometry Dash World and Geometry Dash SubZero, featuring their own levels and music.

Geometry Dash is a side-scrolling platformer. The player takes control of an icon and must navigate through levels until reaching the end. Classic gameplay uses an auto-scrolling camera, requiring the player to use a single button to complete each level. The level restarts from the beginning if the player collides with an obstacle. A practice mode option allows checkpoints to be placed that the player can restart from, though this mode doesn't reward certain collectibles. In platformer levels, players can move left or right without the auto-scrolling camera and can access preset checkpoints without using practice mode.

Various gameplay elements can affect the movement of the player icon. Jump orbs (rings) and jump pads can give jump boosts. Jump orbs allow the player to gain extra height in mid-air. Portals (gates) can change the players gravity, allow the player to teleport, or can change the game mode. For example, the default Cube game mode allows the player to perform jumps, the Ball game mode lets the player change gravity, while the Ship game mode allows the player to fly. The Dual game mode duplicates the icon, allowing the player to control both at the same time or each individually in Two-Player mode. Other elements may change the player's speed and size.

Each level has an accompanying song. Timing and rhythm are crucial, and the music often synchronizes with a level's gameplay and design elements. Geometry Dash includes 26 developer-made levels, four of which are platformer levels located in The Tower section. Each level is assigned one of six difficulties: "Easy", "Normal", "Hard", "Harder", "Insane", and "Demon". Each Main level contains three secret coins, requiring the player to take an alternate pathway or complete a task to obtain them. The player must obtain a certain number of secret coins before the demon levels can be played.

There are several collectibles and currencies that can be obtained in various ways. Completing classic levels will award the player with stars, and platformer levels will award moons. Levels will also award mana orbs, with 500 mana orbs rewarding a key. Keys can be used to unlock chests in the Treasure Room, which will give various rewards. There are also daily chests which will award diamonds, mana orbs, and may award shards, the first of which also being obtainable through completing quests and certain user-made levels. Mana orbs and diamonds can be used in shops to purchase icon designs (skins) and other cosmetics. Vaults can be unlocked after obtaining certain amounts of collectibles, where entering codes can unlock customization options for the player icon.