Icy Tower

The player starts the game on the tower's first floor. To climb the tower, the player must jump from floor to floor (default control: space bar). The character can pass through the floors from below, but lands on them when falling from above. Once the player has landed on a floor, they can move across its surface using the arrow keys. By moving across the floor, the player builds momentum for the next jump. The character can also bounce off the vertical walls on the left and right edges of the tower, allowing them to switch direction while maintaining momentum. If a player builds enough momentum, they can climb several floors in a single jump. Extended sequences of such multi-floor jumps are referred to as combos. A combo ends when a player makes a jump which covers only one floor, falls off a floor and lands on a lower floor, or fails to make a jump within a certain time frame (about 3 seconds). At the start of the game, the tower's floors are stationary. When the player reaches floor 5, the floors begin to move slowly downward. Every thirty seconds, the floors' downward speed increases and the game tells the player to "Hurry up!" If the player misses a floor and falls off the bottom of the screen, the game ends. It also ends if the player is standing on a floor that moves off the bottom of the screen. The goal is to reach the highest possible floor and accumulate the greatest number of points. Points are awarded based on the highest floor reached and the player's combos (if any). Because the tower is of infinite height, it is impossible to reach the top floor. When the game ends, a replay of the game may be saved for later viewing.

The horizontal length of each floor depends on the player's progress, the version of the game, and a random factor. The floors' appearances change every 100 floors until floor 1000. Floors 0–99: Stone Floors 100–199: Ice Floors 200–299: Wood Floors 300–399: Metal Floors 400–499: Chewing gum Floors 500–599: Bone Floors 600–699: Vines Floors 700–799: Pipe Floors 800–899: Cloud Floors 900–999: Rainbow Floors 1,000 and above: glass

Icy Tower records players' best results in built-in high-score tables. Scores are recorded in several categories including highest score, highest floor and longest combo. Players may also publish their scores in online high score lists which may require players to provide game replays to verify their results. The official Icy Tower list is on Free Lunch Design's web server.

Free Lunch Design created Icy Tower using the C programming language and the Allegro game library. Its designers were inspired by Xjump, a game for the Linux operating system.

On 14 March 2007, a press release was published on the Free Lunch Design website announcing a partnership between FLD and mobile game developer Xendex Entertainment for the porting of Icy Tower to the mobile environment. Icy Tower Mobile (ITM) was released on 6 October 2008. Due to the then-current limitations of mobile platforms, the game lacked several features in its PC counterpart, such as recording or sharing replays, and changing game characters. On 24 September 2009, a Free Lunch Design game named Icy Tower Facebook (ITFB), developed on the Adobe Flash platform within the development framework of the Facebook social networking website, was released. It allows players to compare their results with results of their friends within the Facebook system. Players can also personalise their in-game avatars and unlock additional game levels (so-called towers) corresponding to various game styles in the PC version of Icy Tower by exchanging them for coins, the game's virtual currency. In November 2012, an official continuation of Icy Tower, Icy Tower 2, was released for iOS and Android. The producer estimates that on 23 November, the number of downloads of Icy Tower 2 downloads surpassed one million. There are also unofficial, player-developed Icy Tower ports for the Nintendo DS and PlayStation Portable game consoles.

The internal structure of Icy Tower allows for making changes to the character, soundtrack, sound effects, and game palette through downloading and installation of repackaged resource files. Since version 1.2, Icy Tower allows for the use of skins to create additional custom characters which can replace the three default characters provided in the game package. Making a new character is done by creating an image file of a specified structure, containing the various poses needed to animate the character. It is also possible to create a more complex add-on using WAV sound files, which will modify the game's soundtrack and sound effects.

There are a number of tools to help players train, change the game physics, or analyze their own results.