Black Mesa is a beautiful update of a cult game. The environments are more detailed and alive, which makes the whole thing more immersive and pleasant to cross (although Half-life was already a slap in its day).
While remaining true to the original, developers had the good idea to adjust / edit some sequences to make them both more likely and modern. They also added dialogues to better understand what is happening and what is expected of you (without taking the player by the hand of course it remains Half-life).

Short. If you want to play the game of 1998 but it seems too austere in modern times, Black Mesa is a great alternative.