Half-Life: Day One

Half-Life: Day One is the initial pre-release demo of Half-Life. It was designed exclusively for OEM partnerships and was often bundled with graphics cards. It was never available to the general public. Half-Life’s proper demo (available free to the general public), is Half-Life: Uplink, which was released several months after the full game.

Plot
Day One begins at the same point as the full game, but ends after the player completes the chapter "We've Got Hostiles", at the end of the first day of the game's plot. The levels accessed in this demo are overall identical to those that appear in the full game.

Differences
The demo does have some minor differences from the retail version of Half-Life.


 * It is possible to crouch-walk faster.
 * The console and cheats cannot be activated.
 * Direct3D is not supported.
 * The files stored in the .pak files have priority over the files placed in the actual folders.
 * The Glock 17's magazine holds 18 rounds instead of 17.
 * When the Glock is picked up for the first time, it contains 17 rounds, and if an other weapon is selected, the pistol becomes unselectable until the player picks up some 9mm ammo.
 * Up to 25 grenades can be carried instead of 10.
 * Grenades don't explode if they're cooked for too long.
 * It is possible to throw grenades further.
 * The MP5 already has 50 rounds in its magazine when picked up.
 * Four shells are not kept in reserve when picking up the shotgun.
 * The shotgun's pump sound is always heard at the correct time.
 * Ammunition for the pistol and the shotgun contains 30 rounds per box instead of 17 or 12.
 * The Long Jump Module shown in the hazard course looks like a battery instead of a jetpack.
 * The HEV battery has a different appearance.
 * Neither the pistol nor the MP5 reload automatically after emptying a magazine.
 * There is no secondary attack for the pistol; it can only fire in semi-automatic mode.
 * HUD sprites found in the Day One files feature an early RPG icon, an unused battery-style armor indicator, fewer sprites for 320 screen width and 320x sprites that do not feature the bar near the man showing suit power.
 * Partial player profiles system support cut from the final version.
 * Some chapter names are different, although the chapters with different names do not appear in the demo.
 * The HECU Laser Tripmine uses the E3 1998 model, although it was never used in game.
 * Zoom can be toggled by pressing F11.
 * When the player reaches the surface in the chapter "We've Got Hostiles", its daytime instead of sundown.
 * The access to the storage chamber in the beginning of Office Complex (when the shotgun is first found) is not blocked by boxes.
 * There are more vents in the area where the MP5 is found in the chapter "We've Got Hostiles".
 * The area seen during the Resonance Cascade in which Vortigaunts surround Gordon is brighter, its walls can be seen with a flashlight and the player's movement is not blocked.
 * "screenshot" command saves screenshots in broken 8-bit PCX files, while the final version saves them in TGA format. "snapshot" command works the same way as in the final version.
 * Upward looking is limited.
 * Blood effects are different: in Day One blood is flowing while in retail it is splashing.
 * Autoaim is enabled by default and cannot be disabled.
 * The Gman has a different reaction when being shot by the player. If he is fired upon enough times, he will grab his briefcase to chest level and run, apparently scared from the bullets, to the area containing the elevator . This is either an easter egg removed from the final game, or implication that Gordon was to come in slightly more direct contact with him, or even that an event would occur where the Gman runs away.

Characters

 * Gordon Freeman
 * The G-Man
 * Black Mesa Security Force
 * Black Mesa Science Team

Enemies

 * Xen
 * Barnacle
 * Bullsquid
 * Headcrab
 * Houndeye
 * Vortigaunt
 * Zombie


 * Hazardous Environment Combat Unit
 * HECU Troopers

Weapons

 * Glock 17: The most common handgun.
 * Crowbar: The most iconic weapon of the series. Can be used to break crates and weapon boxes, as well to kill enemies.
 * Mk 2 Grenade: The most common used hand grenade. Can be thrown at enemies for an explosive radius of damage.
 * HECU SPAS-12: The most common shotgun used by the HECU. It has high power and causes high damage.
 * Laser Tripmine (Not usable): A laser tripmine device that explodes upon movement.
 * MP5: The most common automatic firearm used by the HECU.

Trivia

 * It is not possible to activate the console, however it's possible both to enter console commands and to see console output.
 * To enter console commands, "gfx\shell\kb_act.lst" file should be extracted from "valve\pak0.pak", a new line in "command" "any name" should be added to kb_act.lst, kb_act.lst should be added to "gfx\shell" of pak0.pak, and a key should be bound to a new command in the main menu.
 * To see console output, the game should be launched with -condebug command line argument. The output will be written into "valve\qconsole.log".
 * Day One DLLs were built on August 31, 1998, and the executable file was built on September 1. Its build number is 676. It is OEM Release Candidate 4, however, the text in top-right corner of the console (cannot be seen in game but can be seen inside engine DLLs) says "Half-Life 1.0 Alpha build 676", possibly a leftover from alpha builds. Executable file version is 4.0.0.1, possibly referring to its Release Candidate number, but version range 4.x was later taken by dedicated server version of Half-Life.