Odin Sphere

Odin Sphere is a two-dimensional (2D) side-scrolling action role-playing game where the player takes control of five different characters across six playable scenarios. Areas within levels are circular stages allowing movement left or right with exits leading to other areas; the main goal in each area is to eliminate all enemies and proceed to the next area. Combat—which uses a beat em up-style battle system—takes place within these areas, and revolves around the player character using a combination of physical attacks and Psypher skills, skills tied to each character's magical weapon. Combination attacks are triggered by attacking enemies continuously.

Jumping can be used to reach airborne enemies within stages. At the end of each battle, grades are awarded based on the battle time, damage taken from enemies, and the amount of damage dealt. The amount of in-game currency the player receives as a reward after each battle depends on the battle grade.

Odin Sphere is set on the fictional continent of Erion, which is divided into multiple nations scattered across the land. The two main nations are the warrior land of Ragnanival, and the forest-bound Fairy Kingdom of Ringford, separated by a wasteland that was once the kingdom of Valentine. At the game's opening, Ragnanival is ruled by the Demon Lord Odin (オーダイン, Ōdain), and Ringford is ruled by the Fairy Queen Elfaria (エルファリア, Erufaria) with help from her nephew Melvin (メルヴィン, Meruvuin). The other nations include the neutral land of Titania; the volcano-bound Fire Kingdom ruled by the one male resident King Onyx (オニキス, Onikisu); and the Netherworld, the land of the dead where natural crystals grow, ruled by the undead Queen Odette (オデット, Odetto).

Two key elements in the game are psyphers, weapons incorporating crystals made from phozon life energy; and the Crystallization Cauldron, a weapon created by Valentine that crafts crystals by absorbing phozons from the land. A driving force of the plot is the tale of the Armageddon, a foretold catastrophe in which Erion is destroyed and the survivors rule the new world.

Odin Sphere was the brainchild of George Kamitani, a video game designer who had worked on Princess Crown, a 1997 Japan-exclusive side-scrolling action RPG developed by Atlus for the Sega Saturn. The game was developed by Vanillaware, a studio created by former Atlus staff including Kamitani to create successor projects to Princess Crown. Initially founded as "Puraguru" in 2002 when it worked on Fantasy Earth Zero, the company changed its name in 2004 when the staff moved to Kansai. It was during his time working on Fantasy Earth Zero that Kamitani met the founding members of Vanillaware.

Odin Sphere, which began development in 2004, was designed as a spiritual successor to Princess Crown, specifically evolving the multi-layered narrative style of the original game. The game's programmer was Kentaro Ohnishi, one of the founding members of Vanillaware. The producer was Atlus staff member Akiyasu Yamamoto. According to Ohnishi, the project started as a direct sequel to Princess Crown, but later became a spiritual successor which incorporated multiple nods to the original game.

Odin Sphere scored 83/100 on the aggregate site Metacritic based on 49 reviews, denoting a generally positive reception and being the 7th best-reviewed PS2 game of the year. Editors of Famitsu Weekly magazine gave the Japanese version a 32 out of 40 cumulative score, earning it the publication's Silver Award, with critics praising the title's graphics and "intuitive" controls, but also remarked that its difficulty was high and many areas of the game looked too similar. Play Magazine awarded it a perfect score, stating that "in the case of Odin Sphere, [we are] confident that this is a perfect game, and that anyone who comes to it will derive the same", praising its 2D graphics, detailed storyline, and unique combat system as high points. Western reviewers generally praised the game highly: the story was cited as both compelling and well-told, with it being compared to the works of Shakespeare and the A Song of Ice and Fire book series.

The gameplay systems and controls were generally praised, but the criticism was laid upon elements of repetition in its combat and progression, and its inventory system. The graphics were unanimously praised, with many comparing it to classic storybooks. A recurring criticism was slow-down during crowded battle sequences.

The delayed release of Odin Sphere led to issues with the company: they needed to start other projects to keep their company going, leading to the development of GrimGrimoire. The development of GrimGrimoire drained the company's funds, forcing Kamitani to take out a flexible loan of 20 million yen to keep the company afloat and fund development for their next projects, in addition to finding new publishers as Atlus refused to take any more of Vanillaware's products until they had seen how Odin Sphere performed commercially. Nippon Ichi Software would handle GrimGrimoire, while Marvelous Entertainment accepted their next project, Muramasa: The Demon Blade for the Wii. The commercial success of Odin Sphere both enabled the development of Muramasa: The Demon Blade and cleared Kamitani's debt. In tandem with their other titles, Odin Sphere helped establish Vanillaware as a respected developer.