According to Digitpress.com, these are the rarest games on playstation (left out prototypes. There were too many and they were in the 9's)
10
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Elemental Gear Bolt Assassin's Case edition
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9
Family Connection Demonstration Disc
NBA 2Ball
Road Writer
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8
Calamity-Adventure 1: The Natural World
Calamity-Adventure 2: People and Traditions
Calamity-Adventure 3: Around the World
Cali's Geo Tools
Cosmic Cookoff: Language Arts
Cosmic Cookoff: Mathematics
Creative Camp
Creative Isle
Creative Journey Lightspan 8 USA
Creative Voyage Lightspan 8 USA
Faire Games: Language Arts Lightspan 8 USA
Faire Games: Mathematics Lightspan 8 USA
Fox Hunt Capcom 8 10/1/1996 USA
K9.5: Live in Airedale Lightspan 8 USA
K9.5: The Hollywood Premiere Lightspan 8 USA
K9.5: The Tail-Wag Tour Lightspan 8 USA
K9.5: We are the Dogs Lightspan 8 USA
K9.5: WebTunes
KazMania: Chaos in KazMania Lightspan 8 USA
KazMania: Trail of Gems Lightspan 8 USA
Liquid Books: Amrita's Tree Credito and the Coyote Lightspan 8 USA
Liquid Books: Far-Fetched Frontier Tales Lightspan 8 USA
Liquid Books: Lety's Favorite Stories Lightspan 8 USA
Liquid Books: Pop-Out Prose Lightspan 8 USA
Releases Liquid Books: The Adventures of Adelita and Bo Lightspan 8 USA
Liquid Books: The
Wandering Path Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Cosmic Quest 1: City Sights Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Cosmic Quest 2: Fairy Tale Island Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Cosmic Quest 3: Race Through France Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Stay & Play 1: In the Clubhouse Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Stay & Play 2: In Mars' Bedroom Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Stay & Play 3: In Lonnie's Classroom Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Walkabout 1: The Natural History Museum Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Walkabout 2: The Shakespeare Festival Lightspan 8 USA
PlayStation U.S. Game Releases Mars Moose Walkabout 3: World Sports Day Lightspan 8 USA
PlayStation U.S. Game Releases Math Gallery Collection 1 Lightspan 8 USA
PlayStation U.S. Game Releases Math Gallery Collection 2 Lightspan 8 USA
PlayStation U.S. Game Releases Math on the Move!: Addition/Subtraction Advanced Lightspan 8 USA
PlayStation U.S. Game Releases Math on the Move!: Addition/Subtraction Intermediate Lightspan 8 USA
PlayStation U.S. Game Releases Math on the Move!: Multiplication/Division Advanced Lightspan 8 USA
PlayStation U.S. Game Releases Math on the Move!: Multiplication/Division Intermediate Lightspan 8 USA
PlayStation U.S. Game Releases Mona & Moki: Drive Me Wild Lightspan 8 USA
PlayStation U.S. Game Releases Mona & Moki: Drive Me Wilder Lightspan 8 USA
PlayStation U.S. Game Releases P.K.'s Math Studio Lightspan 8 USA
PlayStation U.S. Game Releases P.K.'s Place: Carlos at the Races Lightspan 8 USA
PlayStation U.S. Game Releases P.K.'s Place: Daphne and the Seventh Wonder Lightspan 8 USA
PlayStation U.S. Game Releases P.K.'s Place: Hoopo the Seal Lightspan 8 USA
PlayStation U.S. Game Releases P.K.'s Place: Party on the Patio Lightspan 8 USA
PlayStation U.S. Game Releases Psychic Detective Electronic Arts 8 3/1/1996 USA
PlayStation U.S. Game Releases Quaddle Family Mysteries, The: The Case of the Scarce Scarab Garden Lightspan 8 USA
PlayStation U.S. Game Releases Quaddle Family Mysteries, The: The Case of the Scarce Scarab Lobby/Kitchen Lightspan 8 USA
PlayStation U.S. Game Releases Quaddle Family Mysteries, The: The Case of the Scarce Scarab Parlor/Family Room Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Eggs All Around Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Googol Gulch - General Store, Match Arcade Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Googolfest - Arcade Isle, Moon, Feast Isle Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Googolfest - Party Isle, Toy Isle Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Reshaping Googol - Castle Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Reshaping Googol - The Submarine Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Reshaping Googol - The Tower Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: Reshaping Googol - Under the Ocean Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: The Googol Counting Fair - Corral, Fun House Lightspan 8 USA
PlayStation U.S. Game Releases Secret of Googol, The: The Googol Counting Fair - Midways Lightspan 8 USA
Str.at.e.s Analogy-ology! Lightspan 8 USA
Str.at.e.s Match-A-Batch Lightspan 8 USA
Str.at.e.s Matchmania! Lightspan 8 USA
Str.at.e.s Parallel Lives! Lightspan 8 USA
Str.at.e.s Riddle Roundup! Lightspan 8 USA
Str.at.e.s Riddle Wrangler! Lightspan 8 USA
Str.at.e.s Title This! Title That! Lightspan 8 USA
Str.at.e.s Titlerama! Lightspan 8 USA
Team Buddies Midway 8 3/1/2000 USA
Three Decoders, The: Key to the Carousel Lightspan 8 USA
Three Decoders, The: Riddle of the Ring Lightspan 8 USA
Timeless Jade Trade Lightspan 8 USA
Timeless Math: Brainswarm Lightspan 8 USA
Timeless Math: Lunar Base Lightspan 8 USA
Timeless Math: Maya - King Jaguar's Village Lightspan 8 USA
Timeless Math: Maya - Observatory Lightspan 8 USA
Timeless Math: Maya - Search and Rescue Lightspan 8 USA
Timeless Math: Rover Recovery Lightspan 8 USA
Timeless Math: Space Flight Rescue Lightspan 8 USA
Unknown Variable 1: Masque Manor Lightspan 8 USA
s Unknown Variable 2: Raven's Ridge Lightspan 8 USA
Walt Disney's World Quest: Magical Tour Racing Watch Edition
PlayStation Non-U.S. Game Releases Mortal Kombat II Acclaim 8
PlayStation Non-U.S. Game Releases Rakugaki Showtime Enix 8 Japan
PlayStation Non-Cartridge Items Console, Net Yaroze (U.S. version) Sony 8
PlayStation Non-Cartridge Items Interact Memory Drive Interact 8
PlayStation Demos, Samplers, & Non-Games Titan A.E. Demo Disc Fox Interactive 8