For fans of the original Half Life, or for enjoyers of Half Life 2 who have never played the original, this is a must-play. Black Mesa is a complete remake of the original game in Source engine, with modern graphics, physics, etc. Players will find that the Black mesa facility has been masterfully reconstructed in a more modern engine, and that the Xen portions of the game have been improved upon drastically in comparison with the original, while still adhering to the core tenets of the game's storyline and gameplay.