Half-Life: Source is a direct port of the original Half-Life game to Half-Life 2’s Source engine, introducing graphics and AI improvements as well as some subtle level changes. It is available on Steam as part of three packs: Half-Life Complete, Valve Complete Pack and Half-Life 1: Source, the latter also includes Half-Life Deathmatch: Source.
As opposed to an actual remake of the game, it is simply a direct copy of the game's contents. Almost all of the same assets are used, and most of the differences are due to the fundamental features of the new engine (more detailed lighting and water effects, for example). Some additional optimizations have been made, however, such as increased quality textures, the replacement of drawn bitmap skies with 3D skyboxes, and the addition of new or improved atmospheric effects in some areas. The game's front-end user interface has also been overhauled to resemble that of Half-Life 2, with a chapter selection and dynamic menu backgrounds featuring scenes from the game. In addition, all chapters can be selected upon starting the game for the first time, unlike Half-Life. It is not compatible with any GoldSrc or Source mods.
Changes made to Half-Life
- Environment subtitles are supported; however, they are presented below the health HUD.
- Most maps are a lot brighter.
- NPCs now cast shadows.
- At the start of the chapter Apprehension, the puzzle in which floating barrels must be released from a cage to make a bridge, now has a partially sunken metal walkway, raised by the barrels. Also the floating barrels are blue, like those in Half-Life 2.
- The canyon in the chapter Surface Tension has major changes, such as a more realistic look.
- Water has been overhauled to look clean, so it is easier to see through it.
- Pressing the "USE" key through a wall is no longer possible. A good example is in the chapter Questionable Ethics, where the player could skip the surgical unit and laser event.
- Peters' corpse appears near the surgical unit, while it was only gibs in the original Half-Life.
- Bullets can penetrate through breakable glass panes without breaking it.
- Some crates require more hits to break than the original game.
- In Residue Processing, pressing the switch to halt the crushers on the conveyor will stop them indefinitely until the switch is pressed again, instead of resuming on their own after a while.
- The surgical units in Questionable Ethics stop and start slowly after pressing the button, while in the original Half-Life they stop and spin instantly. So take care not to run into the units while it's moving, as it can heavily injure or kill the player.
- Most interaction sounds, such as buttons, doors, and breakable objects, are reused from Half-Life 2.
- There are a few differences regarding the soundtrack. For example, "Nuclear Mission Jam" plays not only during Questionable Ethics, but also earlier, at the start of the chapter Apprehension. Another example is that there's a noticeable delay before "Jungle Drums" starts playing in Gonarch's Lair.
- It is possible to increase the rate of fire of the Colt Python, SPAS-12 and Crossbow by quick switching after each shot. This is especially effective when using the SPAS-12's slower secondary attack (whereas for the primary attack and for the two other weapons the increase is minimal). However, this method is only useful at close to medium range.
- When the HD pack is used, the method can also be done on the M4's M203 grenade launcher (whereas on the original MP5 it can't, due to the slow drawing animation).
- The idle animations of the Crowbar and the Tau Cannon are now properly shown in-game.
- The Crowbar deals double damage, so it kills Headcrabs with a single hit in Easy and Normal difficulty.
- The Glock 17 has increased recoil, so the player should fire slower shots at longer ranges.
- Originally, the pistol held 18 rounds per magazine instead of 17, but this was fixed in a 2013 update. However, picking up ammunition still grants the player 18 additional rounds in reserve.
- The Colt Python's scope can be used in the singleplayer story by using the sv_cheats console command (despite the visual model still lacking the scope).
- The reloading time now matches the actual animation, which means the player can only fire the revolver when the full reloading animation ends (whereas in the original Half-Life it can be fired when Gordon is about to insert the bullets).
- The MP5 deals more damage, the same amount as the Glock 17 (8 per bullet instead of 5).
- The MP5 has increased recoil, so it is mostly effective at close range.
- When firing the SPAS-12, the player still needs to release the button between shots in order to hear the pumping sound (whereas this was fixed in the original game and its expansions).
- The Crossbow's bolts are affected by gravity, so users firing over long distances must account for this drop by aiming slightly above the target.
- Crossbow bolts can pin enemies to walls.
- The Gluon Gun's firing sound is lower pitched than in Half-Life. In fact, the sound file remains unaltered in-game, whereas the original game increased the pitch.
- The secondary attack button can also be used to fire the Gluon Gun like normal (this is the case in Half-Life: Opposing Force as well).
- The effects of Rocket and Grenade jumping are much more effective than in the original Half-Life.
- A direct hit of grenade on scientists or Security Guards' heads will kill them instantly if they’re friendly to the player.
- The Satchel Charge has a shorter throw distance.
- Laser Tripmines are placed at a slower rate, and unlike the original Half-Life, it is not possible to jump on them (though there's an exception: in Surface Tension, the player can jump on some tripmines in the core of the missile storage room without triggering an explosion).
- If the player picks ammo before owning its corresponding weapon, the ammo HUD symbol won't appear. For example, the grenade ammo for the MP5 in the boxes during Residue Processing (while the weapon is found in the next chapter).
- When a player dies, the camera is no longer fixed laying on the right side. It is now fixed ahead, and their currently equipped weapon will be visibly dropped. However, if the player dies from falling from a great height, the screen will cut to black. These occurrences are the same as Half-Life 2, with the exception that here the screen doesn't flash in red during a normal death.
- If the player is killed with a weapon that inflicts high damage, they will not be gibbed upon being killed.
- When an NPC is killed, the bodies will turn into ragdolls instead of using a dying animation.
- When an NPC is killed without being gibbed, it will become a permanent ragdoll and cannot be gibbed with the Crowbar or explosive weapons.
- NPCs can be killed while performing a script (e.g., the scientist hanging from a ladder in the chapter Office Complex).
- The gibs act more like plastic, as evidenced when a gib hits a wall or the ground. Also, when a gib hits a wall or the ground, it will not leave blood behind.
- It is possible to sneak behind enemies, unlike in the original Half-Life, where they will turn around and notice the player when they are close.
- When a scientist sees an enemy, he will run away rather than "dance" in front of the enemy.
- When running away from enemies, the scientists no longer raise their hands. Instead, they run like a Citizen in Half-Life 2 would.
- When the player has a scientist set to follow them, the leaving distance is longer, so they are less likely to stay behind.
- There is a bug after which a scientist opens a door that will provide access to the player, he will keep following the player even after pressing "USE" key.
- Security Guards are less aggressive than in Half-Life. Instead of running after the enemy, they will regroup to the player's position when they are up to 2 meters away while they are ordered to follow the player.
- If the player shoots the guard's helmet while they are passive, the guard will die instantly. However, if he is hostile to the player, his helmet will be bulletproof from 9mm rounds and shotgun buckshots.
- When the guard is shooting at the player, he fires his pistol in automatic mode rather than in semi-auto. However, if he shoots NPCs, he fires in semi-auto.
- If the HD pack is installed, Security Guards will always fire their pistol in automatic mode without accuracy being affected.
- When a Guard takes damage, his rate of fire will increase due to lacking a "stun" animation while firing.
- Security Guards will attack Barnacles when they make visual contact, while they ignore them in Half-Life.
- Security officers no longer attack the player if they see the player kill scientists or other security guards; they will only attack the player if they are provoked. However, they will still say their scripted lines when the player kills allies.
- Marines have a higher rate of fire than in Half-Life, especially the soldiers carrying the SPAS-12.
- Marines are less aggressive, so they tend to take cover frequently and they will run first when they see the enemy first, unlike Half-Life, where they rarely take cover, and spend the rest of their combat firing the player at range.
- Marines will instantly notice a dropped Grenade and run away from the explosives when thrown.
- Voices are slower than in the original Half-Life.
- Gas mask soldiers' helmets are vulnerable to Crowbar attacks, but they are still bulletproof to 9mm bullets and shotgun pellets.
- When a Vortigaunt hits the player with their beam attack, it has a different hit sound. Occasionally, if Vortigaunts hit the player's head with the beam, sparks will emit.
- In Half-Life, the Gargantua will stay in the player's last known position when he's in the unreachable areas. While in Half-Life: Source, the Gargantua will simply walk around instead until the player comes back again, and only attacks the player if he gets too close to them.
- Due to a current bug, the Tentacles cannot damage Gordon nor security guards, so moving past them is extremely easy. However, walking into their pit will still cause damage to the player.
- Also due to a current bug, crossbow bolts and explosives cannot damage the Gonarch; the player has to rely on bullet-firing and energy weapons.
- It is not armored and can be damaged by small arms.
- Its rocket reuses Half-Life 2’s missile model.
- If the player hits G-Man with a weapon, he will make a plastic sound instead of a bullet deflection sound and effect.