Black Mesa: Definitive Edition - 12b - Surface Tension [Hard]

Chapter 12: Surface Tension - Part Two

After obtaining the RPG and defeating the Apache at the cliffside, Gordon makes his way back to the facility in the hopes of picking up the trail to the Lambda Complex. However, he must contend with escalating heat from the HECU as they deploy heavy armor to try to stop Freeman once and for all, in the form of tanks and armoured troop carriers. To make matters worse, organized alien troops have begun teleporting onto the surface en masse, resulting in large three-way skirmishes between them, the HECU, and a hapless Gordon amidst the war-torn surface.

Playlist with all completed chapters:
   • Black Mesa: Definitive Edition (Full ...  

Notes:
If Gordon ascends at any of the other manhole covers other than the one the tank initially blocks, (such as at 0:57), he will be able to score an easy first kill on the HECU before they know he's there, though there really isn't much cover once out of the manhole. This is why I chose to go to the last ladder at 1:42 (also to make the reveal of the tank more suspenseful)
The HECU will only toss the explosive barrels into the water at 1:19 if Gordon is still undetected at that point
There is no way to sneak past the initial tank fight without alerting anyone - even if Gordon sneaks behind the tank as shown at 1:44, it will eventually detect him after moving up to the road, as will the other HECU soldiers
Damaging the main turret of the tank will render its machine guns inoperable, which is a must if attempting to get close to the tank (2:07)
Just like with the Apache, the Tau Cannon can damage the other vehicles shown in this video - the Abrams, the LAV-25, and the Osprey
There are multiple paths that can be taken to get to the elevator in the big tripmine room (10:36)
If Gordon doesn't shoot down the Osprey at 23:29, it will keep deploying troops periodically
The TOW Launcher's crosshair takes the shape of whatever active weapon Gordon has equipped before he uses the launcher. For pinpoint accuracy when firing, equip the Magnum

Trivia:
The tank featured in Black Mesa is based on the real world M1A1 Abrams (1:48)
The tank in Black Mesa is capable of driving around and swiveling its turret 360 degrees. In HL1, the tank could only fire its cannon in a limited arc in front of it and is immobile
The Abrams in BM also has two .50cal machine guns mounted on its turret. Funnily enough, the Abram's shell does relatively low damage (40) when compared to the DPS of the .50cal (6 per shot), even on the hardest difficulty
The Abram's main cannon used to damage anybody close to the tank when it fired due to the shockwave. In the mod version, this meant that HECU soldiers were often unintentionally gibbed when they stood too close to it
In HL1, the manhole that leads behind the tank is also present (1:44), though the tank does not cover the opening
The armoured vehicle at 3:51 is based on the real world LAV-25. In HL1, the same vehicle encountered in this section is an M2A3 Bradley
Ironically, the Apache at the cliffside is able to take more RPG hits than either the Abrams or the LAV
In HL1, it is possible to destroy both the Abrams and the Bradley by hitting their turrets continuously with the crowbar
The Manta/Alien Aircraft is first encountered at 5:26. It is implied that the Manta is able to spawn/teleport Vorts/Alien grunts onto the surface by flying over an area
The HECU sniper first appears at 6:39. Like the Combine snipers in HL2, a laser is emitted to show where he is aiming at. In HL1, their weapons do not have this laser sight
It is impossible to save the scientist at 6:39 - even if the sniper is killed before he manages to shoot, the scientist will still panic and run into the minefield
After dying, the Guard's leg is clipped into the ground. This has been a bug ever since the mod release in 2012 (6:57)
The tripmine room is full of warheads and other ammunition, which explains why Gordon dies even if he detonates a tripmine far away from himself (11:18)
The devs sneakily added a second crate to the lift at 11:47 that Gordon must shoot before it reached the tripmine for the Definitive Edition
In HL1, the Hivehand is found once Gordon reaches the bottom of the elevator shaft (12:15)
Equipping the Hivehand in front of the Guard at 13:41 will elicit a variety of different responses, though only one line plays each time
In HL1, going through the weapons lockup is optional - in BM it is required to pass through this area (17:31)
If Jackson dies, Gordon will still be able to proceed on in the level but the dialogue with the Guard at 17:50 will be different
In HL1, the area at 25:34 featured a M198 Howitzer that was used to blow up the bay doors at 25:40 so that Gordon can continue. In BM it has been replaced with a TOW Launcher, and the doors are opened by an arriving Abrams tank