If you're a fan of Japanese-style role-playing games and the Nintendo DS, there's a small chance you may have heard of Studio Archcraft's Black Sigil: Blade of the Exiled.
The game is a mostly forgotten-about RPG for Nintendo's touch-screen device that drew a ton of influence from classic 16-bit RPGs like Final Fantasy VI and Chrono Trigger, and got some pretty mixed reviews from the gaming press back when it was released for the handheld in 2009. But it had a fairly fascinating development journey, originally being built exclusively for the Game Boy Advance under the name Project Exile, before switching platforms quite late into its development thanks to a "business decision" (essentially the Nintendo DS would be on the market for longer).
According to an interview with Archcraft's Vincent Dehaut, this version of the game was apparently far enough into development "that it wasn’t an easy choice [to make]", but in the past, no builds of the Game Boy Advance version have ever appeared online to give people an idea of how different this was or what was actually completed. Earlier today, however, that seems to have changed as the preservationist group Codebound announced on Twitter that it had managed to acquire a ROM from an anonymous source and that it had released it publicly on archive.org to let people learn more about the game's development.
The released build is dated two years before the launch of the DS version (February 10th, 2007) and only features the first chapter of the game (with chapters 2 & 3 not being present).
It also contains some pretty glaring differences from the final version, including a completely different design for the game's UI, and a debug menu (which can be accessed by pressing the "start" button) that lets you set your levels and unlock items and heroes.