Dark Empire is an unreleased RPG that was in development by Marvelous Entertainment for the GameBoy Advance. This project was previusly unknown, untill an auction for its prototype was posted by Sample_Seller on Ebay in June 2009. As we can read from the item description:
DARK EMPIRE for the Gameboy Advance !!
RARE ORIGINAL SAMPLE/PROMO VERSION !!
FIRST ONE EVER FOUND !!
Will run on any US Gameboy Adance system. Original promo/sample game was never released or completed, game is playable but only around 30% complete. Very good graphics for Gameboy Advance, you have a world map, a castle you can go to and a village. Ingame text is Japanese, developer most probably Marvelous Entertainment.
It’s fun to notice how the developers used some real photos (as one of Mel Gibson from the Braveheart film) as placeholders for the characters avatars in the game, before the final ones were finished. The gameplay would have probably been like a traditional RPG / SRPG, and looking at one of the photos added in the auction it seems that there were some 3D scenes too (maybe for the combats?).