As of Version 0.05a, 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 34 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.
#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.
#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.
#25 "Prayer" by EBroxas72 - See the Praying event in the Ice Chapel.
#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.