Half-Life came out way back in 1998. Even though more than 12 years have passed since its release, the game is still popular. More gamers play the first HLDM than the second one. Many gaming publications named Half-Life Game of the Year. Thanks to the game's popularity, add-ons were developed: Half-Life: Opposing Force, Half-Life: Blue Shift, and Counter-Strike, the most popular computer game today. Notably, today there are no computers that this game would not run on.

The GoldSrc engine used in HL is a reworked Quake engine. The engine is capable of much more than is used in Half-Life and the games that followed. The Source engine, used by Half-Life 2, Left 4 Dead and others, is a further development of GoldSrc.

The most popular map for Half-Life 1 is crossfire. This map is set as the default on many servers. The modifications made of it are countless.

The most popular modifications of the crossfire level:
ag_crossfire
adv_crossfire
crossfire_emperors
and others...

There are also slightly less popular Half-Life maps.

A list of less popular maps:
fling
rapidcore
doublecross
killbox
levels
the_beach
and others...

A distinctive feature of Half-Life map design is the presence of secrets, where weapons, medkits, armor, developer comments and so on are hidden. You will not find anything like that in Counter-Strike maps.

Of course, it is hard to call the game perfect. There are many bugs in Half-Life that have already become part of the game itself. If they were removed, much of the dynamics of Half-Life as we know it would be lost. Besides bugs there are errors, and those are much worse. The most common Half-Life errors and how to fix them.

There are many Half-Life game modes. The most popular modes used on servers are described below.
Standard game modes:

DeathMatch. The most ordinary mode. Everyone plays for themselves. The player is given a crowbar and a pistol; other, more powerful weapons are scattered around the map for the player to pick up. Whoever kills the most opponents wins.
Team DeathMatch. The same as regular DeathMatch, except that players are split into teams (scientist, helmet, gordon, etc.)

Non-standard game modes:

Fun. A non-standard mode. A special mod is installed on the servers. Each player is given a certain set of weapons, or all weapons. Do not slack off on such servers, because the game pace there is high. Such servers are also called "meat grinders".
Rune. The player enters the game with the usual set of weapons. Besides the arsenal already scattered around the map, there are also runes; picking up one of the runes gives the player a certain ability (super strength, speed, vampire aura, etc.). You cannot pick up more than one rune.
ZXC. Weapon attacks are changed. For example, the MP5 can fire plasma balls, and so on. Each weapon has several alternative attacks.