- The game was originally called Halfbrick Zombies and was a multiplayer game inspired by Smash TV, with as much chaos as possible. It was going to be released for Xbox Live Arcade, but was cancelled due to underperformance of previous Halfbrick Fridays games. Then Sony offered Halfbrick to make some games for then-new "PSP Minis", with the original concept of Halfbrick Zombies being reworked into a single-player game.
- There was going to be a world based on Roman Empire with three Gladiators as a boss battle, which never made it to the final release.
- If Professor Brains opening portals to other dimensions and telling Barry that he'll enslave his favourite characters in World 8 sounds like something that would be followed up by a series of crossover worlds, that's because it was. Alongside the Season 2 overhaul, Halfbrick had plans to make new levels where Barry would visit worlds of Ghostbusters, American McGee's Grimm, Ozombie and BigHead Bash. Unfortunately, all of them were Quietly Cancelled before any further information could come out, possibly due to the poor reception of Season 2. This concept would be used in Halfbrick's another video game, Dan The Man. Specifically in Fright Zone DLC, where Barry travels to the titular protagonist's world and teams up with him to defeat Brains, making it a Fully Absorbed Finale of sorts.
- 2010 and 2023 versions of the game have an unused 5-minute long theme
hidden alongside other music files. According to the comments from Luke Muscat and Jesse Higginson (Lead designer and Composer respectively), this was the original theme pitched for the game. The file consists of many smaller tracks that would switch between each other the further the player lasts during the dash. Later on, different locations with their own music tracks were introduced, and the theme was scrapped. - Early promotion material for Halfbrick+ used footage from 2020 version of Monster Dash. The version of the game that would eventually be released is the original 2010 version, implying that either the decision to release the original version was made very late in development or 2020 version was used as a placeholder.
The game was going to be a small project made in 4 weeks, set to be released as a free gift for Halfbrick fans. It was then delayed and had many things changed. Luke Muscat discusses most of these at
2012 GDC Postmortem and
in his own video on the game's development.
- Each run was originally going to start with Barry breaking through the window, complete with few front-facing sprites. This was replaced with breaking the wall on the left to save the pain of drawing said additional sprites, as well as making an entrance feel less weirdnote The window sequence took place at the center of the screen, had Barry run to the left to get the jetpack, then start moving right, which didn't flow very well. and more dynamic.
- The game's main theme went through many iterations. One of the first ideas was dramatic and futuristic track known as Serious Joyride, which was more in line with Jesse Higginson's music for previous Barry Steakfries games. The other known tracks that were going to serve the same purpose were Hardcore Joyride and Jazzy Joyride.
- Although Barry was always a One-Hit-Point Wonder, a health system was also in consideration to make the game less intensive. The main two ideas were 3 Hearts system (exactly how it was in Monster Dash) or Regenerating Health (A system used by many First-Person Shooter games of the time like Call of Duty, and was also used prior in Age of Zombies). The solution came in with Bad As Hog from Monster Dash, which inspired the vehicle system and made additional hit points redundant.
- Developers wanted to include regular Power-Ups, including the slow-mo and shield. Those would be scrapped for being boring and uninspiring, with vehicles effectively replacing the need for them. Some of the ideas would be reused as Gadgets, and others would be implemented as proper Power-Ups 5 years later.
- Bad As Hog was going to retain its red coloration from Monster Dash. It was decided to make it black in the final release.
- Mission system also went through a lot of changes. At one point, developers considered optional missions (players were able to choose between grind-based mission and difficult mission and complete the one they wanted) and Daily Missions. Additionally, an experience points were considered, before being replaced by a much simpler stars, each mission giving up to three of them.
- Completing a mission would have given player an option to choose a reward between coins and the box. The latter would have given a collectible item, ranging from a lump of coal, headphones, and a pony, to friendship, a space station, and an entire Hawaiian island. According to Luke, it didn't work out because people always chose the box and the items themselves were completely useless without an entire collectible card game that would sit on top of Jetpack Joyride.
- There were going to be a special pickup items, that would add additional points to the distance score. Additionally, players could earn bonus distance points by getting "Close Calls" with Zappers. The latter mechanic was repurposed for one of the Missions.
- After getting hit by a Zapper or Missile, Barry would be vaporized and turned into dust instead of flying additional distance. Something similar would be added in 2023 with Half a Brick gadget, which turns Barry into a brick upon getting KO'd and landing on the ground without additional bounces.
- Original announcements of the game refered to Legitimate Research as Maxtreme Industries.
- When the game was playable during the public events, jetpacks had different◊ descriptions◊ and were planned to have unique stats, so that the speed of rising, dropping and changing directions depended on what jetpack you are using. In the final game, the only significant difference between them is the way they interact with scientists.
- Back in 2013, the development team toyed with a concept of "the asynchronous card-based multiplayer" for Jetpack Joyride. The idea involved cards that would change certain aspects of the game, such as replacing the floor with lava or making tokens explode when collected. The combinations of them could be sent to other players for them to try to complete. This idea was eventually released as a separate app for Halfbrick+ service, titled Jetpack Joyride Test Labs, but with multiplayer aspects removed and cards being renamed into Modifiers.
- Open Beta builds featured a Freemium Timer with Energy currency and the limit of 30 points, each run costing 5 of them. The game allowed various ways to earn more, such Daily Rewards (Which were quite common and tend to grant another 30 points), Energy Generator in the Factory, or as one of the rewards for watching an ad at the end of the run. One of the few reasons why the full release became an Apple Arcade exclusive was to get rid of this system and other Microtransactions altogether. Blueprints were added as a replacement, used to upgrade the vehicles.
- Arctic Industries (then known as Arctic Reactor) used to be quite bluntly based off the stereotypical depiction of the USSR. The laboratory looked more like a Soviet factory from the second half of the 20th century, featured a lot of propaganda posters written in Russian, Saint Basil's Cathedral used to appear in the background and one of the enemy robots was designed after a Matryoshka. Apple Arcade has a policy against using stereotypes, so the laboratory was revamped to look more like a generic basement from Arctic, and a Matryoshka robot was redesigned to resemble a penguin. This also affected Mikhail, who was since referred to as Mik and underwent a notable Costume Evolution (Compare how he looked like◊ in the beta builds to the final release◊). There are still few remnants of the original idea, such as some of the scientists wearing Ushankas and spotting orange mustaches on top of their gas masks and the lab's music resembling Russian Folklore songs.note In fact, the music direction seems to not be affected by the policy at all. When each main boss got their own themes in July 2023 update, Mik's took heavy inspiration from hardbass, which is memetically stereotypical in itself.
