This is alternate ending of Star Wars Episode III: Revenge of the Sith where Anakin kills Obi-Wan. Game was released in 2005 and is based on the movie of the same name. It centers around Obi-Wan Kenobi and Anakin Skywalker as the Clone Wars come to an end. 

Currently we only found end cutscene (dark version), still looking for in-game cutscenes.

Plot

The game follows the movie storyline very closely, incorporating footage from the movie into the game and blending it well with the game portion itself. It involves playing through the events as either Anakin Skywalker and Obi-Wan Kenobi, with radically different events taking place in either. As Obi-Wan, much of the game is centered around destroying General Grievous, while the Anakin levels chronicle his fall to the dark side of the Force and extermination of the Jedi Order. This includes Anakin's attack on the Jedi Temple, which culminates in a duel with Serra Keto, who happens to be the best student of Cin Drallig, who Darth Vader later fights and kills along with Keto. The game ends with the duel on Mustafar between Darth Vader and Obi-Wan. There are two different endings to the final battle, the first being that Obi-Wan defeats Anakin like in the film, the second being that Anakin kills Obi-Wan then meets the Emperor who gives him a new red lightsaber, Anakin in turn kills the Emperor and claims the new Empire for his own.