Unused Content are features that got rebooted or cancelled, though they may be reused in the future.
Mechanics[]
Armor[]
Armor would've been a new type of HP which couldn't be regained. Polyhex has stated that this feature will not be added due to it requiring a large rework of the HP system.
Skills[]
Bomb Mobility[]
The Bomb Mobility icon appears to be a skill or perk related to holding and possibly transporting bombs. It is possible that players with this skill are able to grab, hold, toss or carry bombs around, which could be used offensively or defensively.
This has been added in the form of Gift Wrap
Human Cannon[]
The Human Cannon icon appears to be a skill related to a cannon, and possibly the act of being launched out of said cannon. It is speculated that players would be able to get into the cannon and launch themselves across the map, akin to the Lobby's Cannons.
Wobble Protection[]
The Wobble Protection icon appears to be a skill related to a bubble of sorts. It is highly likely that this is an early 
Bubble Barrier, though it could also be more akin to the 
Bubble Wand's bubbles. The icon also looks quite similar to 
Bubble Ride's icon. However, its icon has since been removed and replaced by 
Fire Meteor.
Sword Skills[]
These swords would've acted like different versions of 
Smack, only being able to used at a close range, however unlike Smack they would've dealt damage and applied different statuses.
Shadow Blade - Would blind players like 
Ink Blast.
Sword - A basic sword without any effects, most likely doing the most damage out of all three swords.
Frozen Edge - Would freeze players. Its icon has since replaced by 
Cold Snap.
Popsicle[]
The Popsicle icon appears to be a blue popsicle. Polyhex has not stated any info about this skill, however it is presumed that it would've applied freezing in some manner similar to 
Cursed Pizza and also would've been part of an unfinished Summer Skill Pack, considering that all other seasons have their own Skill Pack, and the summer theme of popsicles.
Mend[]
The Mend icon appears to be an Armor-related skill, presumably acting like 
Heal but granting Armor instead of HP.
Paintbrush[]
Paintbrush would've allowed the user to draw bricks underneath them to stand on, allowing for movement across lava and large holes.
Poison Zombomb[]
Poison Zombomb would have most likely been the skill version of the Poison Zombomb, allowing the user to drop a Poison Zombomb to chase down other players.
Perks[]
Random Bomb[]
The Random Bomb icon seems to be a bomb with a question mark on it. It's possible that this was an earlier icon for the 
Randomizer. This could've also been a perk that disguises or hides your deployed skills much like 
Stealth Mine, hence the question mark on the bomb.
Crystal Shield[]
This perk would've protected you from a few hits, then shattered. It is unknown how many hits it would protect for. It was added on v3.28.0 as the Crystal Shield.
Wall Climber[]
The Wall Climber perk would've probably allowed players to climb walls.
Protector[]
This perk would probably have acted like 
Tank but adding armor instead of health.
Double Charge[]
This perk was intended for giving you extra storage for your current skill allowing you to use it two times if you please. This extra storage recharges separately from the first one, meaning that two sodas are needed to fill both.
More Unused Decals:[]
Trello Leaks[]
New Perks/Bombs
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New Events[]
Potential bombs spawned by the Rare Bomb event.
