The game's title refers to the guardian of the Master Emerald, in this case Knuckles, who goes on a quest for the salvation of the Master Emerald. All of the guardians of the Master Emerald have gone on a quest to save it. This is Knuckles' quest.
Knuckles: Odyssey of the Guardians follows a much more different style from previous 2D Sonic games. The game's design appears to be more "magical" and artistic, featuring different kinds of environment, each with its own atmosphere. It does not feature a significant plot, rather than very short inner cutscenes which reveal little about Knuckles' adventure.
The game features no significant plot and minimal narrative. However, it features short cutscenes which reveal some plot. While guarding the Master Emerald in Angel Island, Knuckles begins to hear voices coming from the Master Emerald which assigns him on an unknown mission.
The game's gameplay and visual style is very similar to typical 2D platformer-puzzle games like Limbo, Rayman Origins and Braid. Knuckles is the main character in the game, as well as the only character in the game. The player is able to control Knuckles in a 2D environment, moving him left, right, up or down, into small passages, climb walls, dig underground and glide. All models in the game, including Knuckles and enemies are 3D but appear as 2D. Knuckles has a very small number of attacks. He can only use his fists to attack, throw boulders or dig underground and charge from bellow. Throughout the stage, the player can collect items such as traps which he can keep and use later on. The gameplay sometimes briefly switches to 2.5D.
Throughout the stages, the player must solve multiple puzzles in order to continue such as move boulders to clear the path, throw stones to open switches, use ropes to go on, etc. The player must pick up certain items in order to continue such as weapons and information. The environment is mostly dark and mysterious, featuring different types of enemies and obstacles such as Eggman's robots, creatures, animals etc.
At the end of the second act of a stage, the player comes across a boss fight which he must defeat and claim a certain part of that boss e.g. his armor. During some parts of the stage, where it is very difficult to get across or the atmosphere gets mysterious, the music fades out and eventually disappears.
Unlike most 2D Sonic games, Odyssey of the Guardians does not feature acts. Instead, the player controls Knuckles in one enviroment which changes throughout the game. For example, the stage changes from a city to a jungle while gameplay. Throughout the stages, the player encounters bosses he has to face.
- The City: The game begins in an unknown ancient mythical city in flames. There are burning trees falling, ancient stone buildings collapsing and waterfalls with debris. As the player continues, he exits the city and walks into a burning forest with debris.
- The Forest: A forest turned to ashes, with white trees, spiders an poisonous flowers. The player must solve several puzzles to get through contaminated rivers.
- The Cave: The story continues as Knuckles enters a giant fallen rotten tree log which becomes a massive cave. The player has to dig most of the stage and collect treasures. The stage becomes very dark at certain parts which causes the player to lose sight of the character. Therefore, Knuckles must use his treasure he has collected throughout the stage to help him along the way, such as a lighter. Near the end of the stage, Knuckles is pursued by a giant purple centipede, the size of a truck. The player must quickly make his way out of the cave as quickly as possible.
- The Mines: As soon as Knuckles exits the cave, he ends up in abandoned mines and oil factories. In this stage, the player must solve multiple puzzles, most of which involve using pumps to drain the oil, pressing switches to activate platforms or carrying weight to put on libras and open gates. There are several minecarts the player can use to make his way faster to the next level and avoid obstacles. Near the end of the stage, Knuckles must climb on a steel rope to reach the top of the abandoned factory. The action takes place during sunset which transforms the whole stage into orange. There are also many fumes coming from the factories and as a result, the player is only able to see Knuckles' shade.
- The Lake: The action takes place at night, where the full moon shines above a crystal lake. In this stage, the player must guide Knuckles through the light areas and avoid the dark areas where enemies lurk. There are leeches and poisonous fishes in the lake which the player must avoid by building a small boat or gliding above the deep waters of the lake. The puzzles in this stage include Knuckles having to use rocks to activate catapults, use fire to burn enemies and use mirrors to reflect the moonlight onto switches and open secret passageways.
- The Canyon: A misty canyon with steep cliffs and boulders. Knuckles has to climb up several spiky walls to make his way through rocky passageways. There are eagles flying which Knuckles can grab and fly short distances. Puzzles in this stage include the player having to roll boulders and create small hills in order to pass through certain parts and many other.
- The Bridge: As Knuckles goes on in the canyon, the mist keeps getting more dense. Eventually, Knuckles ends up in an enormous wooden rope bridge hanging miles above the air. The bridge is narrow and at some parts fragile and broken. It is miles long and at some parts where the floor has been broken, the player must solve certain puzzles to continue. At some part of the stage, the player encounters a sleeping stone guard who suddenly awakes and fights Knuckles. After defeating the boss, the bridge begins to collapse. Knuckles runs for his life as the bridge collapses behind him. Unable to reach end, he glides and disappears into the mist. The player never reaches the end of the bridge.
- The Winds: Unlike all other levels, in this level the player controls Knuckles while gliding in the sky through clouds and storms. The player must avoid thunders, birds and tornadoes. At the end of the stage, Knuckles enters a big thunderstorm and disappears once more. It does not feature any puzzles and is a very short level.
- The Junkyard: Knuckles ends up in a steel mountain later revealed to be a massive destroyed giant robot of Dr. Eggman. As the player goes on, there are more discarded destroyed robots everywhere. It is a very difficult level as there are many tricky puzzles awaiting the player. He must use switches to activate magnets to attract the junk and open the passageways, make his way through labyrinths, construct little robot helpers to assist him etc. The main enemies of the stage are Dr. Eggman's half destroyed robots who attack Knuckles. At the end of the stage, Knuckles again faces a boss, a robot by Dr. Eggman who uses parts from other robots to reconstruct itself.
- The Island: After defeating the boss in The Junkyard, Knuckles ends up in a pier. The player must construct a small boat from the robotic parts. After creating the boat, Knuckles sets sail for an island across The Junkyard where a green light is visible. The stage is once again misty and dark and the waters filled with robotic debris. Once Knuckles reaches the island, the player makes his way through a dark beach and into the mysterious island.
- The Hill: Following the green light, Knuckles makes his way into the mysterious island, climbing a mountain. It is avery difficult stage, featuring many mind-bending puzzles, obstacles and enemies. The enemies in this stage are animals which appear to have mechanical parts. Abandoned cranes can be seen in the background and at some parts, Knuckles must use them to pass through certain areas where the surface has collapsed. The stage is very creepy and dark.
- The Unknown: The final stage of the game, as well as the most difficult to pass. While passing through the mountain, Knuckles ends up in a base on top of the mountain. There are magnetic pillars surrounding it which create a forcefield. The player must solve a series of puzzles as well as defeat enemies to destroy the forcefield and enter the base where the green light is coming from. After entering the base, the player finds himself in a dimension through time and space where he must solve more puzzles and collect items to open doors. At th end of the stage, Knuckles reaches the green light but a giant Eggman robot is guarding it. After defeating the final boss, Knuckles enters the portal and disappears.
After completing the stage, a cutscene reveals that Knuckles was strapped to a brain-washing machine that allowed his mind to travel elsewhere while Dr. Eggman harnessed the Master Emerald's power. With the help of the Master Emerald's magic powers, Knuckles was able to break free from the machine. He then attacks and defeats Eggman, takes the Master Emerald and leaves for Angel Island.
The music for the game is composed by Jun Senoue, a frequent collaborator of Sega. The game's music features multiple ambient sounds such as bird hummings, rain, wind etc. The music for the game is dark and mysterious in order to fit the eerie enviroment and atmosphere. During some parts of the stage, where it is very difficult to get across or the atmosphere gets mysterious, the music fades out and eventually disappears leaving only ambient sounds.
Knuckles: Odyssey of the Guardians
Knuckles: Odyssey of the Guardians received mixed to positive reviews from critics. Metacritic gave the game a 72 out of 100 criticizing the game's similarity to previous action adventure puzzle games. Positive reviews came from IGN who gave the game a 7.6 out of 10, praising the game's atmosphere and visual style. Nintendo Power gave the game a 7.5 out of 10 saying: "With magical atmosphere and memorable graphic design, Knuckles: Odyssey of the Guardians manages to captivate the gamer's attention". Game Trailers also gave a positive review, a 7.2 out of 10, mostly for the game's level design and music.
Negative reviews came from Eurogamer who gave the game a 5 on a scale of 10 criticizing the game's lack of story, dull gameplay and simple puzzles. Destructoid gave the game a 5 out of 10 focusing on the game's minimalistic puzzles and story. The lowest rating came from 1Up who awarded the game a B+ mostly for the game's gameplay and similarity to other platformer games. Many critics also criticized the game's irrelevant title.
- The Bridge level is based on the episode "Jack and the Scotsman" from the 2001 series Samurai Jack.
- This game marks Knuckles' first appearance in an iPhone.
- A working title for the game was Knuckles: A Quest Through Time and Space.