For an unknown future update, we'd like to encourage players to create more Frightfest and Winterfest versions of levels to be officially included in the game. There's no official deadline for submissions or anything, and... Quite possibly, this could even just be an extra little bonus thing that gets tacked on to every update as people complete more levels, who knows. There's no set plan for any of this, but... filling out the holiday lineups is cool 
When making these levels, don't forget to double check with already-existing Frightfest and Winterfest levels to see how they handle things, including skybox, sun color, the shapes and textures they use, and where. And, of course, Frightfest uses Halloween Trance, and Winterfest uses Xmas Trance. Don't be afraid to get a bit creative, though!
Here's a list to keep track of which levels have already been done, or what's in progress. If there's a level(s) you want to take, reply to this post to sign up to do so!
Blue means in the game already, Green means done, Yellow means in progress
Frightfest:

When making these levels, don't forget to double check with already-existing Frightfest and Winterfest levels to see how they handle things, including skybox, sun color, the shapes and textures they use, and where. And, of course, Frightfest uses Halloween Trance, and Winterfest uses Xmas Trance. Don't be afraid to get a bit creative, though!
Here's a list to keep track of which levels have already been done, or what's in progress. If there's a level(s) you want to take, reply to this post to sign up to do so!
Blue means in the game already, Green means done, Yellow means in progress
Frightfest:
- King of the Marble: Matan's "King of the Ghosts"
- King of the Ring:
- Hunting Around:
- Inferno Ring:
- Sprawl: Matan's "Uncovered Crypt"
- Playground: Matan's "Creepy Grounds"
- Marble Agility Course:
- Blast Club:
- Marble City: Matan's "Pumpkin City"
- Gems Ahoy!: Matan's "Ghosts Ahoy!"
- Triple Decker:
- Acropolis 2:
- Maximo Center:
- Cube Isle:
- Bowl:
- Triumvirate:
- Battlecube:
- Duplex: Yoshi's "Oobleck"
- Gem Finding Folly:
- Ziggurat:
- Requisite:
- Points of the Radar:
- All Angles: Matan's "Fallen Angels"
- Skatium:
- Cragmire:
- Fun in the Sun:
- Apex:
- Triple Trail:
- Skate Battle Royale:
- Core:
- Gems in the Road:
- Skate Park Square: Matan's "BLOODY BATTLE SEWERS"
- Vortex Effect: Matan's "Frightful Roads"
- Outlook:
- Epicenter: Matan's "Spookicenter"
- Marbleland: Matan's "Spookyland"
- Marble It Up!:
- Battlecube Revisited:
- Horizon:
- Concentric:
- Pyramid:
- Treasure Box:
- Tilo:
- Sweep:
- Lupus:
- Vibrancy Grounds:
- Promontory: Matan's "Necropolis"
- Terrace Tundra:
- Ramps Revamped:
- Nadir:
- Megas:
- Par Pit:
- Architecture: Matan's "Abandoned Warehouse"
- Zenith: Matan's "Lake Pungent"
- Eye of the Storm:
- Sacred:
- Citadel:
- Cascade Falls:
- Platinum Construction Co.:
- Prophetic:
- Basin Hill:
- Parkour Peaks:
- Spires: Matan's "Bat Megalopolis"
- Agility:
- Hikaru's V Shape:
- Good to be King:
- Triple Deckers:
- Incidious:
- Archipelago:
- Grassy:
- Quartile:
- Rink Ring:
- Timbertown:
- Green Resort:
- Gravity Tower:
- Sprawl Evolved:
- Layered:
- Sphere Plates:
- Green Mess:
- Landscape:
- Poolside Panic:
- Gym:
- Blender: Chop:
- Wrap Zone:
- Wonky Waters:
- Meridian:
- Exoplanet:
- Mogul:
- Heart of the Typhoon:
- Two Levels:
- Fault Line:
- Ring:
- The Dragon Room:
- SkillPlex:
- Nukesweeper Revisited:
- Polysoup:
- Brown Hills:
- Centroid:
- King of the Marble: ???'s "Kring of the Marble"
- King of the Ring: Yoshi's "King of the Rink"
- Hunting Around: ???'s "Hannukk Around"
- Inferno Ring:
- Sprawl: ???'s "Sprawliday Special"
- Playground: ???'s "Sleighground"
- Marble Agility Course:
- Blast Club: ???'s "Blessed Club"
- Marble City: ???'s "Snowball City"
- Gems Ahoy!: ???'s "Gems, Ho Ho Ho!"
- Triple Decker:
- Acropolis 2:
- Maximo Center: ???'s "Maximart Supercenter"
- Cube Isle:
- Bowl: ???'s "Nog Bowl"
- Triumvirate: ???'s "Treeumvirate"
- Battlecube: ???'s "Tinselcube"
- Duplex:
- Gem Finding Folly: ???'s "Gem Finding Flurry"
- Ziggurat: ???'s "Krampus's Lair"
- Requisite:
- Points of the Radar:
- All Angles: ???'s "All Angels"
- Skatium:
- Cragmire:
- Fun in the Sun:
- Apex:
- Triple Trail:
- Skate Battle Royale: ???'s "Snow Tubing Battle Royale"
- Core: ???'s "Coal"
- Gems in the Road: ???'s "Gingerbread Road"
- Skate Park Square: ???'s "Snow Tube Square"
- Vortex Effect: ???'s "Polar Vortex"
- Outlook:
- Epicenter: ???'s "Festivecenter"
- Marbleland: ???'s "Jingleland"
- Marble It Up!: ???'s "Carol It Up!"
- Battlecube Revisited: ???'s "Tinselcube Regifted"
- Horizon: ???'s "Deck the Horizon"
- Concentric: ???'s "Consantaric"
- Pyramid:
- Treasure Box:
- Tilo:
- Sweep:
- Lupus: ???'s "Tarandrus"
- Vibrancy Grounds:
- Promontory: ???'s "Peppermintory"
- Terrace Tundra: ???'s "Tiding Tundra"
- Ramps Revamped:
- Nadir: ???'s "Reinadir"
- Megas:
- Par Pit: ???'s "Present Pit"
- Architecture: ???'s "Up on the Rooftop"
- Zenith: ???'s "Snowcap"
- Eye of the Storm:
- Sacred:
- Citadel:
- Cascade Falls:
- Platinum Construction Co.:
- Prophetic:
- Basin Hill:
- Parkour Peaks:
- Spires: ???'s "Poles"
- Agility:
- Hikaru's V Shape:
- Good to be King:
- Triple Deckers:
- Incidious:
- Archipelago:
- Grassy:
- Quartile:
- Rink Ring:
- Timbertown:
- Green Resort:
- Gravity Tower:
- Sprawl Evolved:
- Layered:
- Sphere Plates:
- Green Mess:
- Landscape:
- Poolside Panic:
- Gym:
- Blender: Chop:
- Wrap Zone:
- Wonky Waters:
- Meridian:
- Exoplanet:
- Mogul:
- Heart of the Typhoon:
- Two Levels:
- Fault Line:
- Ring:
- The Dragon Room:
- SkillPlex:
- Nukesweeper Revisited:
- Polysoup:
- Brown Hills:
- Centroid:
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