In Black Mesa you will once again play as Gordon Freeman, the distinguished theoretical physicist in the underground Research Laboratory of Black Mesa, who becomes a hero thanks to a stroke of bad luck. What happens is during a failed experiment, a portal to another dimension opens in the laboratory, allowing a race of aliens with very evil intentions to enter.
Things really go awry when added to the alien problem is that of the government, who, once they find out what is going on, sends special forces troops to silence everything that could be going on--aliens and scientists included.
Gordon Freeman won't have any choice but to fight against every obstacle that gets in his way to stay alive in one of the most exciting adventures in the history of videogames.
The playability of Black Mesa (and in Half-Life, the original) is truly amazing. Despite that the game develops in the first person and you'll use tons of different weapons like pistols, shotguns, machine guns, or weapons from another planet, the game has many exploration and puzzle phases that turn the experience into something much more dynamic.
Graphically, as usual, Black Mesa has a lot more detail than Half-Life, and while it doesn't achieve the level of excellence of other modern titles, it is overwhelming at times thanks to its excellent artistic direction.
Black Mesa is a free mod for Half-Life that every videogame lover should enjoy. In addition, it works on practically any computer that is at most 5 or 6 years old, is completely free, and even lets you to listen to the soundtrack from its website.