Leap Day

Leap Day is a level-based platforming game released on the Apple App Store and Google Play on May 11th, 2016. The player plays as a character who is trying to reach the Gold Cup in each daily level. Levels in Leap Day are released each day and are created by an algorithm.

Gameplay
In each level of Leap Day the player has to reach the Gold Cup at the end in order to complete the level. A new level is released each day, and it is not mandatory for a player to complete a level in order to play the next one. All past levels are available to the player and can be replayed at any time. All levels are generated by an algorithm using pre-made parts, and are identical for every player. If a level is not played on the day of its release, it will be locked in the menu. Locked levels can only be played if the player watches an advertisement. Levels will not be locked if the premium version of the game has been purchased.

Cups
Cups will appear on the level menu for each day depending on how far the levels have been completed. Each level is composed of fifteen checkpoints which the player can activate, all numbered in decreasing order starting at checkpoint 15 and ending at checkpoint 1.
 * [[File:LeapDay_trophy_menu_small_bronze.png]] Going past checkpoint 10 will grant the player a bronze cup﻿.
 * [[File:LeapDay_trophy_menu_small_silver.png]] Going past checkpoint 5 will grant the player a silver cup.
 * [[File:LeapDay_trophy_menu_small_gold.png]] Finishing a level will grant the player a Gold Cup.
 * [[File:LeapDay_trophy_menu_small_fruit_crown.png]] Finishing a level with all fruits collected will grant the player a Fruit Crown cup.

Level generation
Levels in Leap Day are generated from a pool of separately created level chunks. Each level is composed of fifteen checkpoints, with all checkpoints except the last having two level chunks in them, while the last checkpoint consists of a special chunk called and End Zone. For these checkpoints, each level chunk is drawn from a large pool of separate chunks and has set elements such as platforms, spikes, fruits and other objects. Other elements, like enemies, have a set place in the chunk but can be changed depending on the level theme, segment difficulty, daily enemy pool or other factors. Since each Theme restricts what enemies, hazards, and interactive objects can appear throughout the entire level, some level chunks that only work with specific game components will not appear in themes that lack them. Some chunks have multiple similar variants, even though they all follow the same basic principle. Level chunks have a specific order in levels: specific easy level chunks appear at the start, other easy chunks separate from these chunks have a high chance of being generated at the beginning, harder ones are more likely appear at the end, and an End Zone is encountered at the last checkpoint.

A level's level chunks and theme are all arranged following a level seed. The seed is generated from the date of each level, meaning that every player will have the same seed each day and a virtual infinite amount of different seeds can be generated. Furthermore, since level generation is date-dependant, Nitrome does not have to support the game and continue updating it in order for new levels to be made available each day. As new content gets added to the game, the level chunks and elements pool will be increased, making new days more varied to increase the game's longevity.

Level chunks are used up until the level section after checkpoint 1, whereupon an End Zone is encountered. End Zones consist of an assortment of enemies that can attack, hazards, and sometimes interactive objects. Each End Zone is unique to the day it was created for. The background of End Zones consists of walls painted in goal colors and dungeon-like scenery.

All possible enemies that can appear in a level are part of a daily enemy pool. This enemy pool is seed-specific and contains three to four different enemies each day. Most level chunks will contain an enemy slot, which is filled according to the daily enemy pool following a set of rules and restrictions. This means that the same chunk can have different enemies in it on two separate days. Common enemies, which have a basic walking pattern and can be stomped by the player, can appear in various situations and are easily interchangeable. Each daily enemy pool will contain some common enemies which will be used in most chunks of the level. However, some chunks will only accept specific types of enemies, such as flying enemies or enemies which can walk on walls. On these specific occasions, only the fitting enemies will be selected. A chunk cannot appear in a level if there is no enemy from the daily enemy pool which can fit in it.

Similarly to the enemy pool, each day has a set object pool. This pool contains various interactive objects and hazards which can appear in the level. This means that there is a limit to the diversity of objects the player will encounter. Since objects are not interchangeable like most enemies, the daily object pool will also dictate what level chunks can and cannot appear in a level. If a chunk contains objects which are not present in the daily pool, it will not be able to appear in the entire level. Both the enemy and object pool give an overall gameplay theme to a level, with some recurring elements the player has to deal with in different situation, helping each level to feel more unique to the player.

Checkpoints
Each level will start with a bottom room which is identical throughout every level. The room is composed of a cheering crowd with a king watching the player above a giant "LEAP DAY" sign. The date is also displayed right above. Between the 15th and 14th checkpoint stands yet another room which is shared throughout every level. It is a dark room the player will traverse that always has the same platforms. Two creatures appear sitting on couches, facing away from the player, watching a giant television. On the television is displayed a television program that reads "Tomorrow on Leap Day" and shows a preview of the level theme of the next level.

Each checkpoint throughout a level can be activated by the player in order to respawn from it after they die, as well as saving their current fruit score. Checkpoints are composed of a red platform with the checkpoint number (sorted from 15 to 1) in the middle. The wall will be opened on the right, and the player has to go through this opening in order to activate the checkpoint. The first room will contain two chests the player can use by jumping under them. The first one will unlock the current checkpoint for 20 fruits, while the second one will unlock the checkpoint if the player watches a video advertisement (provided that data connection is activated). Yet another opening on the right will lead to a second room with a large chest the player can use to purchase the premium version of the game, which allows them to unlock each checkpoint for free, either manually or automatically. Premium players can toggle between both unlock options for free checkpoints in the options menu.

Gifts
Gifts are unlockable aesthetic objects and currently consist of characters and Selfie poses. As of Update 1, there are ten characters and thirty-three Selfie poses. Gifts are unlocked by advancing through levels as indicated by a progress bar on the calendar screen, this done by adding points to the bar by collecting cups on the current day's level. All cups, including Fruit Cups, contribute one point to this bar. Levels 1, 2, and 3 require three, four, and six points, respectively, while levels 4 and higher require eight points. After level 4, gifts are generally unlocked in a pattern consisting of three Selfie poses and a character.

Stickers
Leap Day stickers are a messaging feature present in the Apple App Store version of Leap Day and usable by iOS devices that are running iOS 10. These stickers can be used in the Messages app in messages to other people. The following stickers are included: Nitrome posted the following images on Twitter:
 * Animated stickers of Yolk in the following expressions: dancing, angry , thumbs up , rage , punching, laughing, in love, doing push-ups, performing a martial arts style kick.
 * An avatar of Yolk that can be dressed up with costumes based on events and holidays. The costumes include: a birthday costume, easter bunny costume, pumpkin, St. Patrick's Day costume, pancakes with syrup and a pan, Santa Claus beard and hat, bird, and halo.
 * Stickers of enemies.

In app-purchases
Leap Day has an in app-purchase called premium. It removes advertisement from the game. Also, every checkpoint is automatically registered.

Announcements
Nitrome has released various announcements for Leap Day.
 * Leap Day/2015-16 announcements - Announcements from 2015 and 2016.


 * January 27th, 2017 - Nitrome posted a short video preview of marching enemies that will be added in a future update.
 * February 10th, 2017 - Nitrome posted a preview image of the Valentines update.
 * February 11th, 2017 - Nitrome posted on Twitter that they are aware of the glitch with the horned monsters.
 * February 14th, 2017 - Nitrome posted on Twitter that the Valentines Update had been released.
 * March 16th, 2017 - Nitrome posted on Twitter that they are aware of the two inaccessible fruit on March 16th, and will fix it in an update. They later posted that this update has been released on the Apple App Store and contains some new aesthetic content.

Development
During development, Leap Day was called Project Jump. Leap Day was worked on at some point before being temporarily put on hold during the time period of February 25th, 2015 to April 15th, 2015 in order to finish the first major update to Magic Touch: Wizard for Hire. At this point the game was in very early development, with the general game running and some of the game's art and enemies created.

The game was initially revealed on March 30th, 2015, to make up for announcing that Nitrome Touchy would be discontinued, and Nitrome provided some information on the game's gameplay and also some mockup shots of the game. A single section of the game was used as the basis for each shot, only with a different background and different themed enemies for each shot. At this point in development the game was planned to be endless instead of level based.

By July 24th, 2015, the game had entered mid development. On October 3rd, 2015, Nitrome mentioned that previously work on the game had slowed down due to the team behind it being affected by "various things", and out of the three other games being developed it was the least complete one, despite being started first. Despite all this, Nitrome added that the game's development should now be progressing at a faster pace.

Nitrome posted on December 23rd, 2015 a video of Leap Day's gameplay and also shared information about the game's gameplay. From January 20th, 2016 onward, Mat Annal on his Twitter account and Nitrome on their Twitter account posted preview images of Leap Day. On February 11th, 2016, Nitrome announced that the game's official name would be Leap Day and shared a preview image of the game.

On February 21st, 2016, Nitrome said that they were aiming to release the game in March 2016, but they were not able to meet this release period. On April 21st, 2016, Nitrome posted that the game had been submitted to the Apple App Store and Google Play. The following day, they also posted a video on Youtube of the generated level for April 20th, 2016. On May 4th, 2016, Nitrome announced that the game would be released on May 11th, 2016, and posted on Youtube a trailer of the game. The game was released on May 11th on the Apple App Store and Google Play. Nitrome released nine content updates for the game in 2016.

Mat Annal, one of the game's artists, was aiming for an art style reminiscent of what was considered by fans as Nitrome's "classic" style.

Leap Day's gameplay progression was the result of one idea Nitrome had for an endless game with traditional gaming levels, as during the company's general game development, Nitrome was thinking of ways for its games to combine the endless genre with a level based system.

All employees in Nitrome's office helped create level parts for Leap Day, as opposed to just the game's artist and programmer creating these level parts.

While Amazon App Store and browser ports of Leap Day were initially planned, as of February 2017 Nitrome does not currently plan to release them.

Beta elements
Early on in the game's development (February 25th, 2015 to April 15th, 2015 ) Leap Day was intended to be endless and have no set end point. This had been changed by December 24th, 2015.

Enemies were changed at different stages of development.
 * In the March 30th, 2015 preview, early versions of three enemies are seen:
 * Spring heads and spike heads have a slightly different colour pattern and design. Spike heads have a bigger spike and the spring head has a taller spring than in the final version.
 * A small blob is present, which was cut from the game. This small blob was from an early idea where the regular sized blob would split into tinier blobs when jumped on.

The Waterfall theme originally had fish jumping out of the waterfall, but this was changed due to not looking very good.

During development, the walls for levels were intended to have a light coloured block every ten blocks, but this was removed due to limiting level design. This can be seen in the March 30th, 2015 preview and also in the December 23rd, 2015, video preview.

Unused content
In the April 2016 calendar of levels, April 19th has a checkerboard graphic, the same graphic used for May 11th in the May 2016 calendar. This graphic exists on April 19th because this day was used as a starting point for the calendar during testing of the game's alpha builds. This graphic is normally inaccessible in the game as levels are only accessible from May 11th, 2016, onward. This date can only be accessed if players change the date on their device to April 19th, 2016, or a date prior to this, although Nitrome does not recommend that players do this.

Some Nitrome games are configured so that they can be played with a USB QWERTY keyboard plugged into the mobile device, and even though Leap Day is not configured for this, there are still keyboard inputs that will affect the game. Pressing X will cause the game to fade into white and then end this effect, the same effect seen when hitting a checkpoint chest. Pressing A will cause the game to quickly pan horizontally then be pulled back to the room the player is in, panning to the right when outside of a checkpoint, and to the left when inside a checkpoint. Pressing Esc will pause the game the same way the pause button pauses the game.

Version 1.0
This version was released on May 11th, 2016 on the Apple App Store and Google Play and is labelled Version 1.1 on the Apple App Store. This was the game's initial release version.

Google Play update version 1
This version was released on Google Play on May 11th, 2016, and fixed a bug with the player suspending or resuming playing the app when watching an advertisement.

Adjustments update
This update was released on May 27th, 2016 on Google Play and on June 3rd, 2016, on the Apple App Store and is labelled Version 1.2 there. This update makes adjustments to the game based off problems players were having with the game. For players who have bought Premium, automatic checkpoints can be toggled on and off, and with this change the "Checkpoint Charlie" achievement can be obtained. For non-Premium users, when unlocking a checkpoint the animation for unlocking a chest was changed to make it clear that a checkpoint was being unlocked and the words "checkpoint unlocked" now appear. Social network sharing options were added and the amount of jumps the player could perform was reset when jumping and landing on an enemy.

A glitch with the flames of fire blocks appearing in their block was fixed, along with other bug fixes.

Google Play update version 2
This update was released on May 31st, 2016, and is labelled version 1.23. It is not known what changes this update made to the game. This update's update notes are the same as those from the previous update.

Update 1
This update was released on June 13th, 2016 and is labelled Version 1.30 on Google Play and the Apple App Store. This update adds new content and fixes bugs. The Selfie cam was added. The gifts system was added and with it forty-three gifts, ten of these gifts being the characters Lick, La Beef, Kepi, Meep, Smooch, Solder_26, Root, Scalp, Grill, and Zweiclops, and the other gifts being Selfies, with each character getting three.

This update also fixes the following glitches: the game crashing when the "restore purchase" button is selected in the credits menu, the game scrolling after a level is completed, and for users who have bought Premium the auto-checkpoints toggle button not appearing. The Apple App Store version also corrects the game's splash screen on iPad and shared images on iPad being cropped.

Some level chunks were also modified so that they were easier to complete, one of these being the level segment seen on the June 10th, 2016, level directly after checkpoint 4. This change was not mentioned in the Google Play update notes.

Apple App Store update version 1
This update was released on June 14th, 2016, and is labelled Version 1.3.1. This update makes small adjustment to the sharing function and changes the pop-up that reminds the user to download the latest update so that it does not appear when the user has no internet access.

Version 2.0
This content update was released on July 4th, 2016 and is labelled Version 1.3.2 on the Apple App Store and version 1.30.7 on Google Play. This update adds new level chunks, the total amount added being ⅓ more than the amount currently in the game and adding over three hundred chunks ; two backgrounds, Totem and city; and two music tracks to go with each new background. This update also fixes several bugs.

Version 3.0
This update was released on July 14th, 2016, and is labelled Version 1.3.3 on the Apple App Store and Version 1.30.9 on Google Play. This update adds End Zones, the Beach theme, fixes some minor bugs, and updates the game to Version 3.0.

Version 4.0
This update was released on September 1st, 2016, and is labelled Version 1.3.4 on the Apple App Store and Version 1.30.10 on Google Play. This update adds yolk cannons, logs, slime, Guillotines, bullet cannons, fireball cannons, barrel cannons, liquid cannons, Wall lasers, and rotating blocks were introduced. This update also adds the characters Logga, Rasbunny, and Venus, along with their respective Selfies. This update also fixes a bug with projectiles from enemies being reflected.

September 9th, 2016 update
This update was released on September 9th, 2016, on the Apple App Store and Google Play.

Update 2
This update was released on September 12th, 2016, and is labelled Version 1.30.11 on Google Play and 1.3.5 on the apple App Store. This update added new level segments, easy level segments that appear at the start of a level, and changed the algorithm that makes levels so that these level segments are introduced at the start of levels. This update also fixes a glitch with timer tiles becoming invisible. The Apple App Store version of this update adds cloud saving.

Stickers update
This update was released on September 14th, 2016, on the Apple App Store and adds stickers, a new feature introduced in iOS 10.

Bug fixes update
This update was released on September 26th, 2016, on the Apple App Store and September 27th on Google Play. It is labelled Version 1.3.7 on the Apple App Store and Version 1.30.12 on Google Play. This update fixes a bug with barrel cannons, springs, and makes minor optimizations and bug fixes. The Google Play versions adds cloud saving.

Update 3
This update was released on September 29th, 2016, on Google Play and September 30th on the Apple App Store. It is labelled Version 1.30.15 on Google Play and Version 1.3.8 on the Apple App Store. This update adds the characters Croak, Slab, Whip, Glug, Flake, Tuft, Char, and Turret, along with their respective selfies.

Jump bubbles bug fix
This update was released on October 13th, 2016, on Google Play and on October 14th on the Apple App Store. It is labelled Version 1.30.16 on Google Play. This update fixes a bug with the player's allotted jumps being reset after hitting a jump bubble.

Apple App Store update version 2
This update was released on October 18th, 2016, and is labelled Version 1.3.10. This update lowers the app's minimum iOS version down to 8.0 instead of 10.0.

Version 6.0
This update was released on the Apple App Store and Google Play on October 31st, 2016, and added the electricity theme and fish skeletons. This update caused these new game components to appear on the October 31st, 2016 level, to coincide with Halloween.

Update 4
This update was released on November 3rd, 2016, on the Apple App Store and November 4th on Google Play. This update is labelled Version 1.3.12 on the Apple App Store and Version 1.32 on Google Play. This update adds new End Zones and fixes minor bugs.

Version 7.0
This version was released on the Apple App Store and Google Play and adds new End Zones and fixes a few bugs.

Apple App Store update version 3
This update was released on November 4th, 2016, and is labelled Version 1.3.13. This update fixes a glitch where the player character could become a white blob.

Version 8.0
This update, also called the Winter Update, was released on December 21st, 2017, on Google Play and the following day on the Apple App Store. The update is labelled Version 1.36 on Google Play and 1.3.14 on the Apple App Store. This update adds the Ice Temple, Snow Land, and celebration Themes, ice and snow interactive objects, icicle hazards, and the two Ice Charger, flying icicle, and Wooly Trunky enemies. This update adds new characters.

Version 9.0
This update, also called the Valentine Update, was released on February 13th, 2017, on the Apple App Store and Google Play and is labelled Version 1.3.16 on the Apple App Store and Version 1.40 on Google Play. This update adds the winged sphere and pink blob enemies and greatly improves the level generating algorithm. This update also fixes a bug where horned monsters would jump up and freeze.

Google Play update version 3
This update was released on February 23rd, 2017, and is labelled Version 1.41. This update changes and improves the level creation algorithm.

Aesthetic update
This update was released on March 16th, 2017, on the Apple App Store and March 17th, 2017, on Google Play and is labelled Version 1.3.17 on the Apple App Store and Version 1.43 on Google Play. This update fixes a bug with two fruit on the March 16th, 2017, level being inaccessible, gives the cups a new in-game animation for being reached, and introduces a new splash screen.

Google Play update version 4
This update was released on April 5th, 2017, and in the update's notes is described as fixing minor bugs and making small positive changes to the level creating algorithm.

Future content
The following content will be added in future updates:
 * Swamp background and sewer background.
 * Several enemies, one of these being walking helmet enemies.
 * Two content updates.

Reception
By May 27th, 2016, Leap Day had received one million downloads across both the Apple App Store and Google Play. For its first and second weeks, it brought in the most revenue out of all of Nitrome's mobile games over the same timeframe.

Feature promotions

 * On May 13th, 2016, it was announced that Leap Day had been featured by Google Play and on the Apple App Store's section "New Games We Love".
 * On June 3rd, 2016, Leap Day was featured on "May's Best Games" in the Apple App Store.
 * On June 23rd, 2016, Leap Day was featured on the Apple App Store in the section "Play as Your Que".
 * On July 7th, 2016, Leap Day was featured on the Apple App Store in the section "The 10 Best Platformers".
 * On September 15th, 2016, Leap Day stickers were featured on the Apple App Store in the UK.
 * On December 7th, 2016, the game was featured on the Apple App Store in the section "10 Best Games of the Year".

Glitches
Sometimes also the barrels can appear at the Golden cup floor falling from the sky randomly. In the same level, when starting from the last checkpoint, player starts from the inside of end zone instead.
 * A certain glitch can cause enemies to appear in incorrect spots. For this glitch to occur, the player has to have a checkpoint unlocked before the section where the glitch happens. The following situations can occur:
 * An extra enemy on the same platform.
 * Incorrect enemy placement.
 * Wrong enemy (e.g. a green runner instead of a red jellyfish)
 * Maggots closer to each other than normal.
 * Enemies stuck on their platform.
 * Destroying some breakable blocks from the platform an enemy is standing in may lead to AI issues such as the enemy not being able to tell where the platform ends, often resulting in an enemy moving back and forward in one spot.
 * Some enemy and projectile hitboxes may interact in unexpected manners depending on the player's position and state. This can lead to the player being able to stomp enemies from otherwise impossible angles. The momentum given to Yolk when jumping can also be carried to an enemy or projectile if they collide at the same moment the player taps jump. This can result in enemies being pushed slightly upwards or projectiles changing trajectories and moving diagonally.
 * If the player taps jump at the exact same frame they are about to touch the face of a wall spring, Yolk can grab the spring as if it was a normal wall and slide on it, being able to wall jump normally.
 * If the player is clinging to a wall and a pig reaches the edge of its platform, they will perform their turning animation but move backwards.
 * In September 17 level, the barrels can fall through thin platforms making get through them nearly impossible, since there's no spikes on the next floor they fall. They however will disappear after few seconds. Sometimes Barrels gets even to a checkpoint floor. Touching the barrels in this floor warps the player back to the start of the level. Player then must go to menu to return to the last checkpoint saved.

Trivia

 * The following elements are similar to content from the Mega Man video game series:
 * The sound effect for jumping on an enemy and killing it is the same as the sound for shooting with the Mega Buster.
 * The creation of the death sound for Leap Day's main character was influenced by the death sound of Mega Man.
 * The dying animation and teleporting animation for Leap Day's main character is similar to the respective animations for Mega Man.
 * The July 20th, 2016, level was hinted with many preview pictures showing the Beach background and the End Zone challenge.
 * The levels shown on the shop pages of the game do not appear on their respective days.
 * The September 22nd, 2016, level includes an End Zone from September 3rd, 2016 as a normal chunk during the level.