As of Version 0.08, wallpapers have been added to Uneven Dream, viewable on both Kubotsuki's and Totsutsuki's PCs. Both characters share the same set. There are currently 53 wallpapers to unlock plus a custom slot to insert the player's own wallpaper. Below is a gallery of all of them and their unlocking conditions.
Wallpapers
#4 "A Trip to Metal World" by 001247 - Interact with the large fleshy trees in Metal Mounds until the panorama changes for a second.
#5 "Bad Joke" by gummy - Enter the innermost room in Clownpieces.
#6 "Mysterious Mime" by gummy - Find and interact with both Mimes in the Metal Mounds.
#7 "Breeze" by Jojogape - Find and obtain Totsutsuki's Cape effect.
#8 "Angel" by EBroxas72 - Enter the Angel Room in Purple Town.
#9 "My dreams so far..." by peppe_ykoba - Find and obtain the following Totsutsuki effects: Sunflower, Star, Music Box, Cape, UV Light, and Nightcap.
#10 "See, it's a crane!!" by gummy - Obtain the Origami effect and use its Shift action.
#11 "...Someday I'll learn" by EBroxas72 - Visit the Peeper Room in Winter Village.
#13 "Chased" by EBroxas72 - Get caught by both types of chasers currently in the game.
#14 "Winter Dawn" by EBroxas72 - Sit on what's depicted in the wallpaper in the Winter Village.
#15 "The Showroom" by sniperbob - Enter the Sandy Showroom for the first time.
#16 "Handicraft" by CrystalCreation - Obtain 5 effects for each character.
#17 "Pyrotechnican Dreamers" by EBroxas72 - See both the Turtle Hole and Origami Flight events.
#18 "Spotlight" by 001247 - Obtain the Sunflower effect.
#19 "Graph Fight" by 001247 - Obtain the Pencil effect.
#20 "A worm?!" by Rurima - See the Appleworm's Birth event.
#21 "Blue Lovers" by gummy - See the Blue Lovers at Bumblebee Lounge.
#22 "On Deck" by gummy - Visit the Playing Card Maze.
#23 "Tickled Pink" by gummy - Visit the Pink Desert.
#24 "Radio Tower Outlook" by CrystalCreation - Visit the radio tower outlook in Rainy Garden (ver0.07 and earlier)./Obtain the Lily of the Valley effect (ver0.08).
#25 "Prayer" by EBroxas72 - See the Praying event in the Ice Chapel.
#26 "Terror Terror Bozu" by gummy - Visit the industrial path connecting from Stone Wasteland to Isometric Street.
#27 "PR0C355_F41L3D" by Rurima - Interact with the arcade machine in Concrete Treehouse that depicts a girl whose face is blacked out.
#28 "One Night, Cold Springs" by eltd - Visit the tubes in the Light Spa.
#29 "Make Your Mark" by eltd - Obtain 10 effects for each character.
#30 "The Nothing Store" by eltd - Visit the store (Geschäft) in Starlit Road.
#31 "I like the colors here" by EBroxas72 - Sit on the bench in Neon Park.
#32 "Below the Sunset" by EBroxas72 - Visit the pier in Windmill Lake.
#33 "Dormir Demais" by Rurima - Reach the main area of the Subconscious Garden.
#34 "Kubo Drift" by maple - See the 78 Skidoo event in Cube Road.
#35 "At the Top of the World" by 001247 - Reach the top of Forsaken Cliff's tower.
#37 "Incoming Traffic" by knuxify - Find the toys in Fast Food World.
#38 "Cosmic Rest" by rollaby - Have the Nightcap effect in inventory and visit the main area of Star Field.
#39 "BUY ME" by Moucky233 - Buy at least one item from either shop in Neon Village.
#40 "Kubo on the Mall Roof" by SkipFlow - Reach the roof in Abandoned Shopping Mall.
#41 "The Seer's Vision" by rollaby - Obtain the Seer effect.
#42 "Feeling Better?" by AcceleratingWind - Visit the Deranged Faces Zone.
#43 "Breezy Feelings of Greyness" by AcceleratingWind - Visit the Grayscale Gardenscape.
#44 "Positive Cuteness Never Expires" by AcceleratingWind - Visit the PC98 World.
#45 "Cinematic Cynicism" by AcceleratingWind - Obtain the Fast Forward effect.
#46 "Head of Nightmares" by gr33n - See the Hanged Kubotsuki event in the Playing Card Maze.
#47 "Draw Me Like One of Your French Seals~~~!" by EBroxas72 - Interact with the seal on the couch in either Sea or Water Palace.
#48 "Nail Board on My Head" by GwenDaArtist - Visit the Nail Board.
#49 "Doodles, Doodles Everywhere" by GwenDaArtist - Visit the Doodle World.
#50 "Ode to the Optimist" by GwenDaArtist - See the Goodbye Totsu event at the Heaven's Docks.
#51 "End of a Sweet Dream" by GwenDaArtist - See the Trixboa event in Galleta World.
#52 "It's cold in here" by River - Obtain the Hoodie effect.
#53 "Blinded" by rollaby - Interact with the TV that displays the blindfolded woman in Corroded Dream.
Bonus Wallpapers
Bonus wallpapers are wallpapers that are present in the [Bonus Wallpapers] folder of the game, but are not available in game, either due to being too close to an existing wallpaper, or due to lacking a proper trigger to implement them. They can still be used by using the custom wallpaper feature and replacing the default wallpaper by one of those.