In the early 2000s, Namco & Argonaut Games — the developer of such beloved titles as Star Fox and Croc — released an action platformer for the PS2, GameCube, Xbox, and Windows called I-Ninja.
The game focused on a ninja-in-training who accidentally killed his master while attempting to rescue him and who then sets on a quest to find a series of MacGuffins to defeat an evil emperor. It featured cutscenes directed by the legendary animator Don Bluth and was pretty well-received at the time, with IGN, in particular, giving it an 8 out of 10, arguing: "I-Ninja packs so much personality and attitude into its formulaic design".
A Game Boy Advance version of the game was planned from Namco, DSI Games & Coyote Handheld, but sadly never released at the time. However, now thanks to the efforts of the preservationists over at Hard4Games and GamingLegend64, the unreleased title has finally been dumped online for all to see.
Given the game was originally made for consoles, the Game Boy Advance version of the title is understandably very different, to fit within the handheld's limitations. The elaborate cutscenes are gone and each level is divided into small sections that try to emulate moments from the console version's stages, such as the game's Goemon-Esque giant mech battles and Super Monkey Ball-like barrel riding sections.
It also features a fairly impressive 3D effect for the Game Boy Advance, with players being able to run in and out of the screen and turn the character to face the camera.
You can watch the full video from Hard4Games documenting this discovery above (note: the game has been redumped since the video first went live fixing some of the issues referenced within). You can also grab the prototype now from archive.org to try it out yourself.