The player can unlock playable characters by earning points in the most current level of Leap Day. Most characters have identical behaviours and three selfie poses.
Each character moves left to right, turning back when they hit a wall. The player can make their character jump by tapping on the screen. Characters can make one additional jump while in the air, in which they curl into a spinning ball. The double jump count is reset upon leaving any surface. This includes touching the ground or wall, jumping on an enemy, bouncing off a spring or getting a boost from a jump bubble. It also resets when going through a teleporter.
When characters come in contact with a wall, they grab onto it and slide down until they jump away from it or interact with something else. If the player does not jump when sliding down a wall, the character falls back to the ground directly below or starts walking in the other direction if the wall meets the ground.
The playable characters are vulnerable to all hazards and enemies and die immediately upon direct contact with most of them from the side. Some enemies can be killed by jumping on top of their heads, which rebound the character upwards. Upon death, a character is respawned at the last checkpoint the player activated.
When playing the game itself, the player can hit the camera icon located just below the pause button at the top right corner of the screen to take a selfie. This takes a screenshot of the game screen as the player is currently viewing it, but replaces the character's in-game sprite with one of the character's selfie poses. If the player has no selfie pose for that particular character they are taking a picture with, the screenshot will simply display the character's sprite as presented in-game.
Once the player takes a selfie pose, they have the option of sharing the selfie or cancelling and resuming the game. If they choose to share or save the screenshot, the previewed selfie pose is retained, along with the addition of the words "Leap Day" in red followed by smaller white text reading, "A new level every day!"
Selfie poses are one of the two prizes that can be obtained when the player fulfils their progress bar, however, they can only be unlocked for characters which the player has already obtained. The player can keep track of the number of selfies they have per character based on the number of white camera icons that are shown directly below the character on the selector.
The options and preview screen that pops up when taking a selfie on iOS.
The saved selfie pose with Yolk as seen in the previous picture.
An example of the screen the player sees when they unlock a selfie pose with Nibbler.
VIP characters can be unlocked by purchasing a VIP subscription or beating up to 365 levels. Finishing 90 levels unlocks Eggnog, 180 unlocks Scrambled and 365 unlocks Hard Boiled. The amount of levels required to unlock each VIP character is cumulative. Unlike the normal characters, VIP characters have no selfie poses, but possess certain abilities that can aid the player throughout a level.
Some characters can be unlocked without purchasing them. This can be done by going to the info screen on the calendar menu, then tapping rapidly within the credits screen. This causes a text field to appear, allowing the player to type in one of the codes below to unlock the character:
In the May 19th, 2016 preview for Leap Day, which showed the in-game sprites for the characters that would be added in Update 1, four sprites differ slightly from their final versions: La Beef's head is closer to his body, Grill's skin is much lighter, Scalp's sprite has lighter skin, and the bottom part of Kepi's hat is green instead of grey.
Zweiclops' name is a pun on Cyclops. "Zwei" means "Two" in German.
On November 19th, 2019, following a series of hints on the official Discord, Yolk was revealed for the Smash-like indie crossover fighting game Indie Pogo. He was released on, fittingly enough, Leap Day, 2020. His attacks are references to various other Nitrome games, most of them from the mobile era.
Glug's second selfie contains a character that looks like a female version of Yolk.
↑Nitrome on Twitter:
: Nags Tavon: Just unlocked a new character in Leap Day. Is this some reference to @PlayOverwatch 's Soldier: 76??
Nitrome: yes it is a little nod to that., 17 Jul 16, retrieved 21 Jul 16.
↑Nitrome on Twitter:
: birfdæ: Is the red a hat or a brain?
Nitrome: A red bobble hat., 5 July 16, retrieved 5 July 16.