It's just a sideshow attraction in Guardian Heroes, but Arcade Mode embodies all of the inimitable, brash creativity that has made its maker, Treasure, one of the best-loved game studios. Imagine, having selected your character in Street Fighter IV, that you were made to fight not one but every character in the game, all of whom piled on you simultaneously in an endless survival gauntlet, without so much as a stutter in frame-rate.

It's mayhem. And not the kind of conservative, Saturday morning children's TV mayhem of so many Smash Bros. titles. It's bona fide wild-men-picking-fights-with-rocks mayhem, the sort that, in the blur of colour and shape, makes it difficult to know where your character ends and an enemy begins. But it's also the kind of mayhem that, in some deep place in your being, unlocks the abandoned joy we all play video games in the hope of rediscovering.

Guardian Heroes is the eldest of Treasure's three seminal releases for Sega's Saturn (the others being Silhouette Mirage and Radiant Silvergun, which was also recently re-released on Xbox Live Arcade). It mixes the side-scrolling fantasy beat-'em-up play style of Golden Axe with the combat complexity of Street Fighter II and threads them into an OutRun-style branching structure. As a result, the Story Mode is at once familiar and, in the unique combination of these iconic designs, fresh and enthralling.

You have the choice of five characters to play as (four initially - female knight Serena Corsair is unlockable). Alpha male Samuel Han's brutish sword attacks can swipe through enemies even as they cower behind shields, while the lithe, agile Ginjirou Ibushi complements his super-fast attacks with lightning augmentations. For players who prefer the magical approach, the unlikely-named sorcerer Randy M. Green can employ various types of elemental magic, while Nicole Neil is the only character who can heal herself, an advantage counterbalanced by the fact she has the weakest attacks.

The game is unusually story-heavy for a Treasure release, fully embracing an anime knights-and-castles aesthetic and spinning a tale of regal intrigue that spirals up to the gods themselves. It's told via regular cut-scene interjections between the short, sharp missions.

Unlockable game pics are found deep within the game, badges of honour for those who can find them.

Normally these kind of narrative interruptions would irritate, but in Guardian Heroes, each micro-exchange is followed by one of three Choose Your Own Adventure choices, each sending your team off to a different numbered stage. The branching paths lead to a variety of different endings, and within the stacking choices you make as you play through the game, you have the opportunity to define what type of player you want to be, killing or saving civilians, defending or crushing the weak, and showing mercy or cold justice to repentant enemies.

The writing is robust rather than electric (and often the phrasing makes branching choices difficult to distinguish from one another). But the narrative structure ensures that you'll want to play through multiple times as you work to collect all of the endings and unlockable characters, which subsequently become available in the Arcade Mode and player-versus-player online modes.

For all its structural cleverness, the jewel at the heart of Guardian Heroes is the battle system, which allows attacks to be elegantly strung together into creative chains. It works a little like Street Fighter's cancelling, except the windows for combo-ing moves together are far more generous and there is no limit in the number of attacks that can be executed in quick succession. For example, you can trigger Han's 'Finale', which sees the character spin his arms around in a helicopter circle in order to juggle an enemy high into the air. Then, as you and your foe begin your descent to the ground, you can air-dash forward before executing a Han Maximum, weaponising your fall and adding a magical element to slice through your enemy mid-air.