The game was originally planned for release in 2021 to commemorate the 30th anniversary of the Sonic series, but was postponed to improve the quality of the game.

At the time of the announcement, the title of the game was "a high-speed, free-running action adventure", but this was later changed to "an unrestricted, new world action adventure". Unlike the previous Sonic Forces, the new game has a different style, in which the player takes control of Sonic as he runs through the Starfall Islands, a landscape of jungles, waterfalls, deserts, and other various landscapes, and battles enemies.

The scenario was written by Ian Flynn, who wrote the scenario for the American comic book versions of Sonic (Archie Comics, IDW Publishing), replacing Ken Pontac, who had previously been in charge of the scenario, and the number of languages supported has increased to 12.

The tagline is, "Journey into New Realms".

Synopsis

Plot

Knuckles is fulfilling his duties as a Guardian of Angel Island as usual, and he is also thinking about the roots of his own mission.

One day, while on patrol, he accidentally discovers a ruin and activates it, which sends him to another location, where he is attacked by a mysterious hostile entity and is trapped as an electronic body.

At the same time, Sonic, Tails, and Amy, who had detected Dr. Eggman's activity, were both chasing the Chaos Emeralds and Dr. Eggman on the Tornado. When trouble occurred, they were suddenly sucked into a hole in space-time that opened in the sky.

Sonic found himself thrown out into a mysterious space called cyberspace, but he managed to escape and arrived at Kronos Island, one of the zones on Starfall Islands.

Guided by a mysterious voice that spoke to him from somewhere, Sonic started running to find his lost friends.

Gameplay

Sonic will collect Chaos Emeralds and items obtained by solving puzzles and gimmicks throughout the Starfall Islands and by clearing Cyber Space levels that can be entered through portals.

Items

Red Seed of Power

The Red Seed of Power (チカラの実 Chikara no Mi, lit. Fruit of Power) is a red spiky fruit. When given to the Hermit Koco, it raises the level of Sonic's attack power.

Blue Seed of Defense

The Blue Seed of Defense (マモリの実 Mamori no Mi, lit. Fruit of Defense) is a light blue fruit that looks like a melon. When given to Hermit Koco, it will increase Sonic's defense level (the higher the level, the less rings Sonic will lose when attacked by an enemy).

Portal Gear

Portal Gear (ポータルギア Pōtaru Gia) is an item that looks like a gear. By consuming it, you can activate a portal that serves as an entrance to the Cyber Space.

Vault Key

Vault Key (エメラルドキー Emerarudo Kī, lit. Emerald Key) is an item that looks like a key. It can also be obtained by completing missions in each Cyber Space stage. When a certain number of keys are collected, the emerald device is unsealed, and the Chaos Emerald stored in the emerald device can be recovered.

Memory Token

Memory Tokens (メモリーアイテム Memorīaitemu, lit. Memory Item) are items needed to converse with fellow electric bodies states that Sonic's friends are in. Amy's is a pink heart-shaped jewel, Knuckles' is a red medal, and Tails' looks like a yellow wrench. They are also needed to view side stories in addition to the main story.

Skill Piece

A Skill Piece (スキルピース Sukiru Pīsu) is a light blue rectangular item. It is like experience, and by collecting them, skill points are accumulated, and new skills (techniques) can be learned in the skill tree.

Purple Coin

Purple Coin (紫コイン Murasaki Koin) is a purple coin-like item. They can be collected at various locations on the island and at slots that occur rarely at night. By spending them, you can play the fishing mini-game with Big.

Characters

Main Characters

Sonic the Hedgehog

(ENG CV: Roger Craig Smith / JPN CV: Jun'ichi Kanemaru)

The world's fastest and supersonic hedgehog.

This time, he lands on the mysterious Starfall Islands and embarks on a different kind of great adventure to find his friends.

Sage

(ENG CV: Ryan Bartley / JPN CV: Megumi Hayashibara)

A mysterious girl appears where Sonic goes in the Starfall Islands. She warns Sonic to leave the island and sets the Titans in motion.

She mechanically follows Dr. Eggman's orders and is looking for a way for Dr. Eggman to escape from the cyber space.

Sonic's Friends

Sonic's friends have been transformed into a disembodied form called a "cybernetic body" and locked in a cage-like structure. In this form, he is able to hear the Kocos' voices.

Amy Rose

(ENG CV: Cindy Robinson / JPN CV: Taeko Kawata)

A hedgehog girl who is in love with Sonic. She is trapped on Kronos Island, the first island Sonic visits. Unable to leave Koco alone to search for someone, they search all over the island together.

Knuckles the Echidna

(ENG CV: Dave B. Mitchell / JPN CV: Nobutoshi Canna)

A descendant of the Echidna tribe that flourished in prehistoric times, he is the guardian of the Master Emerald on Angel Island and is being held prisoner on Ares Island, the second island Sonic visits. He feels that the ruins of the Starfall Islands and the ruins of Angel Island, where he lives, are somewhat similar.

Miles "Tails" Prower

(ENG CV: Colleen O'Shaughnessey / JPN CV: Ryou Hirohashi)

A genius fox with a penchant for tinkering with mechanisms, he is trapped on Chaos Island, the third island Sonic visits. He uses his natural intelligence to figure out what the relics of the Starfall Islands are for.

Other

Dr. Eggman

(ENG CV: Mike Pollock / JPN CV: Kotaro Nakamura)

A self-proclaimed evil genius scientist with an IQ of 300. Using his newly developed AI, he plans to take over the ancient civilization lying in the Starfall Islands and create the ultimate mecha.

However, he too encounters an unexpected situation and is trapped in cyberspace. While Sage tries to find a way out of the cyberspace, he unravels the mysteries of the space. Besides Tails Tube, it is confirm in this game that Ivo Robotnik is his real name.

Big the Cat

(ENG CV: Kyle Hebert / JPN CV: Takashi Nagasako)

He is a big cat who has been fishing for a long time. For some reason, he has come to the Starfall Islands (he says he was looking for a place where he could fish and ended up there) and is in charge of the fishing mini-game.

Koco

Mysterious stone-like creatures can be found throughout the island.

There are teachers and students, and soldiers in armies, and each place seems to have its own role to play.

Elder Koco

Their are round-looking Kocos with moss growing on their like a beard. When you collect lost Kocos from around the island and take them with you, they will raise Sonic's speed and rings (the maximum number of rings he can carry, so to speak) levels.

Hermit Koco

The Hermit Koco, like Elder Koco, has moss like beard. They too can help upgrade Sonic's levels but by his attacking and defensive power.

DLC

So the DLC that have been released have been promotional or update patches. New content is planed to added in 2023 such as a challenge modes, new outfits, and playable characters (most likely Amy, Knuckles, Tails, and Sage).

Monster Hunter Collaboration Pack

Sonic Frontiers: Monster Hunter Collaboration Pack (モンスターハンターコラボパック Monsutā Hantā Korabo Pakku, lit. Monster Hunter Collab Pack) is one of the DLC collaboration packs for Sonic Frontiers, this one featuring the Monster Hunter series. In this pack, Sonic can wear the Rathalos Armor or Felyne Rathalos Armor as well an exclusive meat grilling minigame that can found at the Fishing Spot.

SE Inugami Korone

Inugami Korone Collaboration DLC "SE Inugami Korone" (戌神ころねコラボDLC「SE:戌神ころね」 Inugami Korone Korabo DLC "SE:Inugami Korone") is yet another DLC collaboration pack but only in Japan. This one is with the Vtuber and current ambassador of the Sonic series, Inugami Korone of Hololive. Sonic can wear Korone-themed gloves and shoes in the DLC and the Koco can have the appearance akin to Listener-san. The sound effects are also switched to Korone's voice clips.

Sonic Adventure 2 Soap Shoes

The soap shoes from Sonic Adventure 2 can be worn by Sonic and can be downloaded in different methods depending on where you live. In Japan it can be downloaded regularly just like the other DLC as Sonic Adventure 2 Shoes (ソニックアドベンチャー２のシューズ Sonikku Adobenchā Tsū no Shūzu). Outside Japan the way to get them is signing up to the Sonic Frontiers newsletter.

Holiday Cheer Suit

Sonic Frontiers: Holiday Cheer Suit, known in Japan as Sonic's Christmas Costume (ソニックのクリスマスコスチューム Sonikku no Kurisumasu Kosuchūmu), just like the soap shoes, is just a cosmetic. This, most likely, is the first time Sonic in his Santa outfit is playable in a game.