A guard zombie can be seen burning after leaving the observation room.A survived scientist will scream for help during the continuous blasts.Isaac Kleiner will admire the Headcrab in the jar.The guard cannot be revived after going out of the test chamber.The player wakes up instead of standing around in the test chamber.Your health will always be 70 after waking up, damaging yourself before the accident will add up back to 70 HP. The player will be damaged by 30 health (armor will not be affected) during the intro of the chapter.When during the harmonic reflux Gordon is experiencing, you will be teleported in one of the Xen caverns from Gonarch's Lair instead of an open Xen area, and during the Vortigaunts scene, you cannot move and the Vortigaunts will try to get you back to Earth.When the sample is inserted, the sample cannot be pulled back.When the sample is delivered, the cart will not move by side-to-side, instead, it's mechanism is changed to move only forward and backward.The monitor will turn into static once the Anti-Mass Spectrometer starts to malfunction.Inside the test chamber, there is a monitor that shows what's going on in the observation room.Isaac Kleiner and Eli Vance now have their respective models.Later, in Unforeseen Consequences, when going back to the observation room, the monitor is not displaying the time anymore, instead, the time can be seen in one of the panels, at that time it was already 9:47 AM. It will change to 9:01 AM once reaching the test chamber. The time, 8:50 AM, is displayed on the monitor on the ceiling.In the elevator, the option to go down via ladder is now locked until Unforeseen Consequences.It can be found near the shelves of the sink. In the locker area, there will be a scientist asking help for a toilet paper, if you want to give him the toilet paper, you can.In Half-Life 1, you can acquire 15 armor, whilst in Black Mesa, you can acquire 30 armor via charging station and battery found in your locker.In the locker area, when acquiring the H.E.V, Gordon will do an inspecting animation and the scientist nearby you will admire how you look with the H.E.V.After exploding the microwave, the guard will mock you with his innumerable list of dirty and clean puns.In the cafeteria, when you explode the microwave, instead of a scientist getting shocked from it, a guard will approach the microwave and say 'Cus uh, that was you-know-who's lunch' retconning Dr.In the cafeteria, instead of one scientist observing everything in the vending machine, a guard will replace his spot, minus the observing part.When seeing the G-Man and a scientist arguing, the G-Man will look to Gordon, thus the scientist will blind the windows.When throwing things or props to scientists and guards (only in this chapter), they will reply to you with the expression of being angry or annoyed.A guard before you enter the lab would say 'Aw man, you cut the ponytail! Sell out.'.Some of the people will greet you or glance at you going to work.Barney can be seen at the entrance of his checkpoint.Later in Anomalous Materials, one of the scientists would say 'Wasn't the tram ride a little longer, today?'.Half-Life's tram ride is estimated to be around 5 minutes, whilst Black Mesa's is estimated to be around 7 minutes, this gives the player a chance to look around inside the Black Mesa Research Facility.When the player dies, it will be a realistic firstperson-view death instead of instantly lying down.When the player dies, the NPC will react to Gordon's death similar to Half-Life 2.All weapons will have inspecting animation when acquired for the first time.The screen will flash green once something teleported.When hitting the vending machine, you can grab them, while in the original, you cannot grab the sodas. The vending machines give 15 cans of soda, while in the original, it only gave 10 cans soda.The G-Man appears more often in Black Mesa.A Half-Life walkthrough is estimated to be finished in 3 hours, whilst Black Mesa is estimated to be finished in around 6-8 hours.Half-Life is made from a modified Quake engine called GoldSrc, whilst Black Mesa is made with the Source Engine.Black Mesa doesn't have a training course, though some of the developers said it was cut for obvious reasons.

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