Gameplay follows the four protagonists as they explore various environments, with different characters fighting enemies using third-person melee or first-person shooter combat.

As Climax's first role-playing game, the team wanted to emulate Japanese RPGs, though the art style was adjusted from its earlier anime-inspired aesthetic to appeal to a Western audience.

Sudeki is an action role-playing game where players take control of up to four characters, exploring a variety of locations including towns, rural areas and roads, wilderness, and underground temples and mines from a third-person camera perspective.

[5] The combat system is a combination of real-time fighting action, and menu-based item and ability selection which slows time.

[4][5] Tal and Buki fight in third-person using timed button combos to execute different melee attacks, being able to move or dodge around them during combat.

Ailish and Elco switch gameplay style to first-person shooter, moving freely around the arena and using assigned weapons to fire projectiles at different rates.

[4][9][10] Characters not under the player's control have customisable behaviour patterns, such as attacking directly, keeping distance, or focusing on providing support.

[5][7] There are different status buffs (health regeneration, attack boost) and ailments (poisoning, slowed movement) which play a role in battle for both the party and enemy groups.

[4][9] Cinematic spirit strikes, which are unlocked by progressing the story, can be activated once a special meter is filled by killing enemies, taking damage, or performing successful combos.

Elco is a Transentian scientist and descendant of Lebius, a friend to both Tal and Ailish; he lost his arm in an accident and was granted a clockwork replacement by Lusica, putting him in her debt.

Tal is then sent to retrieve Ailish from a neighbouring village, and sent with Elco to recover a large crystal from Shadani Mo which can power his defensive shield.

[21] Describing the company's choice, Microsoft manager Peter Connelly said that Japanese developers were failing to deliver RPGs for the Xbox, so Climax Studio's project gave them an entry in an under-represented genre.

[16] The current form of Sudeki began development in September 2000, at the time as a console exclusive overseen and published by Microsoft Game Studios.

Drawing inspiration from the slow-motion action sequences in The Matrix, the team implemented a slowing of time, allowing players to maintain an advantage and strategise without the combat losing its real-time style.

[25][16] He wanted the cast to respond like real people rather than comic book stereotypes, and with that aim in mind the actors recorded together in the same studio, with their performances playing off each other.

[28][23] To ensure minimal load times, the developers directly streamed data through the Xbox's hard drive, cutting down on memory usage.

[23] Finding and addressing bugs was a key job for both Climax and Microsoft, who play tested the game in tandem in Britain and America.

Notable bugs that were found included graphical glitches with character models, and Ailish's tutorial sequence where her healing spell killed her.

[14][21] The environments went through the same process as the character art, with real-world elements incorporated into some locations; the Anthropomorph village of Shadani-Mo drew stylistic inspiration from the Nevada desert and Native American tipis, while Transentia was designed around its "Orwellian" machinery and steampunk-inspired aesthetic.

Of all the characters, Elco went through the most changes; starting out as an Arabic-themed archer, he went through multiple redesigns until the idea of his injury solidified his design into its final technology-infused version.

The dark world of Akloria was built using the Haskilia map, with its buildings marred or destroyed and the environment using washed out and darkened lighting and colours.

[37] Originally scheduled for release in the 2003 holiday season, it was postponed to the following year to allow the developers more time to polish the gameplay.

[41] It formed part of Microsoft's strategy for promoting the console in Japan, principally by tapping into the RPG market that at the time was dominated by the PlayStation 2.

[41][42] As part of its promotion, several notable voice actors were brought in to dub the characters, including Kenji Nojima (Tal), Mai Nakahara (Ailish), Hikaru Midorikawa (Elco) and Yū Asakawa (Buki).

[11] Edge Magazine generally enjoyed the combat and exploration, but felt that it had an identity crisis going on between its complex elements and intended audience of RPG newcomers.

[54] Tom Bramwell of Eurogamer summed up that "despite building most of the game upon fondly remembered Japanese RPGs, Sudeki doesn't really leave us with any that justify the time we invested in it.

"[9] Matt Helgeson of Game Informer said that the main draw for him had been its character customisation systems, with other elements feeling unfinished or unpolished; a second opinion from Lisa Mason praised the genre balance and art direction but found multiple frustrating points.

[4] Christian Nutt, writing for GameSpy, felt that its combat system was a good foundation for potential sequels but it was otherwise an underwhelming experience.

[58] PC Zone shared many points of praise and criticism with console reviewers, also noting several moments of slowdown even on powerful PCs.

[4][10][54][56][59] The combat system and its customisation met with general acclaim from critics,[10][12][54][57][58] though several cited a lack of greater depth and floaty aiming and controls.