Half-Life

Half-Life is a first-person shooter where you play as Gordon Freeman, a scientist at the Black Mesa Research Facility. The action starts when an experiment goes horribly wrong, and aliens from another dimension start appearing in the facility.

Zaukul's Review
Half-Life is an outstanding game. Practically every part of it is far superior to its contemporaries, from the graphics to the characters to the story. It's impossible to understand what an achievement Half-Life is without playing it.

From the very beginning you are completely immersed in the world of Black Mesa. The opening train ride is easily among the best opening in any video game, serving as a great introduction as well as a preview of many things that you will be encountering later in the game.

It's worth noting that Half-Life was the first game to do cutscenes within the game engine without taking control away from the player, doing this both for story progression and for atmosphere. It was also one of the first to have a continuous game world, with brief loads between areas that never take you out of the game.

There are a ton of other great things about this game, and I could go on, but for now I'll end by saying that Half-Life is one of the greatest games of all time.

Played in 1998 and many times since and rated 5.