Half-Life: Day One

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

Story
The story follows the original game and ends in the chapter "We've Got Hostiles". The demo itself is the same as the full game, except for some minor gameplay differences (thus making it non-canon); while crouching, the player moves faster than in Half-Life. The console command cannot be activated on this demo, and installing the HD pack doesn't make any change. Some differences are also the magazine size of the 9mm pistol is 18 rounds instead of 17, and the player may carry up to 25 grenades instead of 10. These grenades don't explode in the player's hands, even if he cooks them for too long, and he throws them to a farther distance than the original Half-Life game. The MP5 already holds 50 rounds so the player doesn't have to reload after picking it up, and the picked up ammunition for the pistol and the shotgun contains 30 rounds instead of 17 or 12. Additionally, the long-jumping module shown in the hazard course looks like a battery instead of a jetpack, and the HEV battery looks different. It should be noted that the pistol and the MP5 don't reload automatically after emptying a clip, so the player has to do it themselves; there isn't any secondary attack for the pistol; it can only shoot in semi-automatic mode.

Mr. Valve's model and the actual valve model are in the game's files as well, but it is unknown if the map "valve.bsp" is also in the demo, seeing its impossible to use the command console on the demo.

It also contains a different player.mdl. It has a female counterpart, using the old holo.mdl head. It also have a extra animation; ambush, where the player is attacked and knocked unconscious. This is definitely made for the end of the chapter Apprehension where the player is kidnapped by a couple of soldiers, and is therefore hinting that it was going to be a cutscene, although it is only speculation.

Weapons

 * 9mm Pistol
 * Crowbar
 * Hand grenade
 * Shotgun
 * Laser Tripmine (placed only, not usable by the player)
 * SMG

Allies

 * Black Mesa Security Force
 * Black Mesa Science Team

Enemies

 * Barnacle
 * Bullsquid
 * Headcrab
 * HECU
 * Houndeye
 * Vortigaunt
 * Zombie