For me Anomalous Materials RULZ! 
Inbound are useless in Half-Life series :fffuuu:
Surface Tension ofc ^^
I’d say Power Up. Don’t know why, I guess I like the terror the Garg brings, along with the fact that you don’t directly fight him, you lure him into his own demise. His stubborness at trying to catch you is his downfall.
Surface Tension pissed me off when i played it first time 
Hazard Course
I love tutorial levels
Office Complex.
Love all the Wrecked Labs and Mutilated Co Workers.
It really Makes my Heart Warm.
Surface Tension
Seeing that huge dam was awesome back then, and then the part where you are on the cliffside
Xen. It’s beautiful, bizarre, mysterious world. I was so stunned when I first played through that levels.
But it comes with a stupid platforming moment
I’ve fallen in love with Questionable Ethics.
Makes you think, don’t it.
It was a great mechanic.
HL1: Questionable Ethics; it was the only chapter that really showed off the lab areas areas of Black Mesa. Plus, the whole Tau Canon sequence was very memorable.
HL2: Highway 17/Sandtraps and Follow Freeman/Anticitizen One; I liked how you could really go at your own pace in Highway 17. I loved exploring all the houses and stuff too. Sandtraps got old with the whole “stay off the sand” gimmick but I LOVED breaking into Nova Prospect with the antlions. Very fast-paced and just plain awesome. Follow Freeman/Anticitizen One had a lot of action and good music, plus the squad thing was cool too.
EP1: Gotta go with Undue Alarm; I loved the whole bit with the Citadel core and the gravity gun. Kind of reminded me of Portal in a way.
EP2: The Vortal Coil; I like the sequence with Gordon, the vorts, and the rebels all fighting to Vortal Combat, one of the best pieces of music in Half-Life.
HL1:
puhh, it’s hard to pick only one chapter because almost all are awesome.
I love the “Intro” (Inbound and anomalous materials plus unforeseen consequences) where everything just seems like its a normal day at work, then you fuck up the experiment and the place turns into pure havok! I love that desperate, terrifying atmosphere just after the Resonance cascade.
Surface Tension was a blast and i love all of Xen for its eerie Atmosphere. When I was younger and played HL for the first time and reached the teleporter just before Nihilanths chamber where you can hear the voices of the security guards and scientists I literally thought I’d go to hell! man, that was some scary shit…
HL2: Same here…
Point Insertion, because you have no idea what the heck is going on and the atmosphere of the dystopian City 17 is amazing.
Then Sandtraps and Nova Prospekt, because it’s a cool turning point: first you have to battle against hordes of antlions and then they are suddenly your allies. It feels badass to make your way through Nova Prospekt with such an army behind your back. Nova Prospekt itself is also very dark, giving a glimpse of what horrors await the citizens who are deported to this place.
Our Benefactors and Dark Energy are also very cool. Not gameplay but story wise and i like the aesthetics of the citadel.
EP1: To be honest, i found Episode One pretty boring. The Idea in Direct Intervention to go right back in the Citadel after being rescued by the vorts was good and the puzzles were fun, but when i think about “AHH” moments in EP1 only the last scene where the citadel blows comes to my mind. The Stalkers were also scary. Apart from that, pretty boring, especially the rescue of the citizens and the strider battle at the end was more labor than fun.
EP2: This Vortal Coil, it has everything: the gameplay mechanics are versatile, it’s a very story driven chapter, i like the vorts, , g-mans heart-to-heart, heck it’s nearly perfect.
Our mutual Fiend was a very impressive location, apart from the run/drive-your-heart-out strider battle which was exhausting.
T minus one has awesome cinematics (the rocket, the advisor battle) and ends with one of the most emotional and nastiest cliffhangers ever.
This thread was aimed at addressing your favorite Half-Life 1 chapter, not analyzing the subjective elements that make chapters from later installments your favorite.
^ Who cares
Anyways, since it’s alive again;
Half Life 1: Questionable Ethics and Lambda Core because the environments were just so alive, and there was always something to do. This is also when you really start to back track and get an appreciation for game’s story and design. But the one scene on the cliffside of Surface Tension takes the cake for me.
Half Life 2: Highway 17 simply because I love rocketing down gunships off the side of the coast. They were so loud and monstrous that their screams of pain and anger gave me goosebumps of epic.
Half Life 2 Ep.1: …the hospital part…?
Half Life 2 Ep.2: Vortal Coil and Our Mutual Fiend.
Questionable Ethics.
The best.
True dat.
I played a game once in which battleships and long-range artillery units could be given names. I named some after Half-Life chapters. Questionable Ethics was the railgun unit I cared most for.
I’ve always liked Residue Processing, don’t know why.
inbound - its all about the narration.
Catseyez, where u at woman. it’s all true.