Pokemon Orange beta nightly is another fan-made ROM hack of a Pokemon game. The 'nightly' designation suggests this is a constantly updated version with frequent changes and potential instability.  It's an early access build made available to players interested in testing the work in progress.  Like other ROM hacks, it likely involves modified Pokemon, story, and gameplay mechanics, all created and distributed independently of Nintendo.

Pokemon Orange beta nightly

Pokemon Fool's Gold 1.3