Rockman DX3, also known as Zook Hero 2, is an an unlicensed pirate game developed by Vast Fame that rips gameplay off the Rockman X series. Just like Rockman X, there are eight stages, and six of them contain a boss who gives you his weapon upon defeat. The protagonist, Zook, also has abilities nearly identical to those of X. Despite these similarities, the code and graphics appear to be completely original and the music is actually decent.
The author, Noxxa, plays the most popular and widely available release, which happened to be released with the final boss stage already unlocked, leading to the incredibly short completion time.