Angel Island does exist, and it can be found in real encyclopedias. You may read more about it here:

Angel Island is a prominent location in the Sonic series. It is the hometown of Knuckles and provides the seat for the Master Emerald. It first appeared in Sonic the Hedgehog 3 as Floating Island but has since adopted the name Angel Island after one of its zones, Angel Island Zone.

Sonic Heroes 2

Cropped map (team-annotated)
Sonic Heroes 2 locations
Team name Member 1: Member 2: Member 3: Member 4:
Team Sonic Sonic Shadow Silver Scourge
Team Rose Amy Blaze Cream Vanilla
Team Underground Tails Cosmo Manic Sonia
Team Knuckles Knuckles Shade Mighty Ray
Team Archaic Mina Max Mach Sharps
Team Big Big Honey Marine Tikal
Team Chaotix Espio Charmy Vector Saffron
Team Covert Ashura Wechnia Nazo Covert
Team Dark Rouge Fang Bark Bean
Team Babylon Jet Wave Storm Hurricane
Team Badnik Scratch Grounder Coconuts Metal Sonic
Team Eggman Eggman Eggman Nega Chaos Emerl Metal Sonic II
Miscellaneous Tiara Froggy Fiona Fox Egg Pawn
Nic Tempest Megatox Guidashir

Angel Island makes an appearance in Sonic Heroes 2. Its contents are broadly in line with its first appearance, Sonic the Hedgehog 2, and contains Casinopolis, Hidden Palace Zone, HydroCity, Icecap, Lava Reef Zone, Marble Garden Zone and Sandopolis Zone from that game. Confusingly, Angel Island Zone also appears in the game despite its surroundings no longer being called Floating Island. As well as housing Knuckles it is a habitat also for Shade in this game. It is also the start of Team Knuckles' storyline, in which Team Eggman shatters the emerald with the intention of releasing Chaos. Unlike most of the canonical games in which Angel Island makes an appearance some of the shards haven't flown far and are only local; shards are collected in Mystic Ruins, Green Hill Zone, Great Turquoise Zone, Angel Island Zone, Reactive Factory Zone, Sandopolis, Oil Ocean Zone and Sky Deck Zone, Angel Island Zone being a zone within Angel Island.

Sonic Riders to the Extreme

Angel Island is the third track in the game and is the third easiest track. It is in the Chaos Emerald Cup.

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