It is possible to do some crazy things with the airboat (often by accident). Strange thing though, I realised that my least favourite part of H-L2 were the vehicle sections. With exception to the showdowns at New Little Odessa, Under the Bridge and Lighthouse Point.
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Arrival at Black Mesa.
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Seeing the rotating alarm lights after the Incident for the first time, and dodging the wild laser that sprung from the broken tube.
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First fight with soldiers
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Blast Pit monster
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RPGing apaches
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Sniping with the crossbow
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Pit Worm and Boss in Opposing Force
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Citadel core in Ep1
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End of lowlife and hospital sequnce in Ep1
All of HL2 and ALL of Episode 2, especially vehicles and urban combat
Same thing with me i loved the graphics of HL2… and i guess you could say HL1 for its time even now the graphics arent BAD but in ep2 id have to say the fight against all the striders won me over… after all those striders and hunters came at me and i killed them all i just sat back and said…“woah”
Half-Life:After the tram ride, you seeing all these scientist having a good time, after that dead body around all monster.
Half-Life2:Train station, i love trown the can to the civil protection,lol. Ravenholm, all i hope going there is for some friend, but not, some “friendly” zombie keep coming for you.
Half-Life 2: Ep1:Low Life, The Fear in the dark, all i could say is pwning zombie with Alyx.
Half-Life 2: Ep2:Killing antlion with two funny rebel, that music is awesome.
The moment in HL when I worked out that Blast Pit was all about getting the rocket ready to fry the Tentacles.
Route Kanal in HL2, on the run from the Civil Protection.
Pretty much all of Ep2, it was awesome.
HL: The canyon. I love the music that kicks in. Any other time fighting the marines. The Half-Life story had some great up and downs as far as climax’s and falls… that was one thing I loved about it.
Op4: Foxtrot uniform (first encounter with Black Ops I think). Mainly the part where you sneak up on the Black Ops messing with the bomb, that was probably my favorite.
HL2: In the beginning when you first fight the (shit, can’t even remember what they’re called… the guys who replaced the HL grunts…). I hated being pushed around and barked at by them, I took pleasure in beating them to pulps and pumping them full of lead.
I also liked the very end, very matrix-y feel to it.
Mine are as follows:
Half Life-Fighting the tentacles
HL2-Crossing the bridge and fighting the gunship
ep 1-Fighting zombies in pitch black or the gunship fight in the top of that destructible building
ep 2-Killing striders with Magnusson devices
MMM mine is from Half-Life one:
When you get to the elevator shaft and the ladder is on the other side, you have to jump to get on it. Then you see a scientist hanging on the elevator ladder and falling. I loved that “splat” noise when he got dropped :].
HL1: The Resonence Cascade :freeman:
Blue Shift: same thing
OP4:When you got the displacer gun
HL2: The Teleporter Scene in the begginning
HL2 EP1: RE: Hospital Edition
HL2 EP2: Strider/Hunter battle
I also liked the Motorboat Part mainly because you dont have the gravity gun yet so the boat auto flips itself back, so you can just do all theese crazy stunts and try and ride on shit to glitch your way out of the area
Half-Life1 the test chameber and getting the Gauss cannon 
Half-Life Blue Shift: Meeting my clones. “Hi Barney clone #10239483128” and the ending was fun
Half-Life Opposing Forces: Being a Marine and the Barnacle Weee go my pet go oh and the teliporter gun exept when it buts me into a hole
Half-Life 2 umm Getting the hell out of Ravenholm (fast zombies scared me ) oh and getting to use my old and trusty friend from Half-Life1 the Gauss cannon (jeeps weapon) shame it wasn’t player based
Half-Life 2 LostCoast: Ummm Ummm Umm… PIE!!!
Half-Life 2 Ep1 Hmm the car ride of course. The Zombie Hostpital. Also Alyx wasn’t tottaly useless.
Half-Life ep2 Hunters, Striders,Graphics!!! thats it
Fave part: [COLOR=‘DarkRed’]Resonance Cascade (in test chamber of Half-Hife)
HL1: when you crawl in a small tunnel and theres a small pool behind you, a soldier open up the lid at the far end of the tunnel and throws in a C4 charge.
i remember stopping for a second thinking “what’s that? OH SH**!” then you had to slooowly crawl back to escape the explosion. i barely managed to get to the small pool and look up, watching the explosion blast itself out overhead.
i was so sure he’d do it again i spent the next 10mins looking for a safer route
cant recall any memorable events in neither blue shift nor opposing force, even though i loved opposing force.
HL2: When the rebels made their assault and the city became a warzone. very well made.
and i THINK it was Ep2 at the start when that large bridge collapsed. ill never forget that.
and OF COURSE on HL1 when you blow up the Pie in the microwave 
i could write moments i loved in portal too but i just dont know where to start
Bit of a cheat, but mine just became this:
https://www.youtube.com/watch?v=X-JGjTSCoa4&feature=channel_page
Omg h4x
Fave parts:
HL : Surface tension, the whole surface part. Marines Marines Marines APCs TANKS FFS
HL 2 : Motorboat and Buggy parts. Also Ravenholm. Proper scary, more proper than in Doom. And Omaha bea… err, antlion nova prospect Assault. IMO the whole NP is awesome.
HL 2 Ep 1 : Finale
HL 2 Ep 2 : Antlion caves and Strider battle
Did I mention earlier that you, Mr. Bean, are revolting?
You always get sum cookies, for nothing.
Hell, you cannot even lock the thread properly…
I’m disappoint…
:’(:’(:’(
Stop trying to pretend you don’t worship the ground I walk on, you’re fooling no-one.
HL1: The early parts of Blast Pit, before encountering the tentacles. Everything felt so derelict; in the entire game, even Xen, there was never a time for me when I felt more alone.
HL2: The part of Route Kanal with the water-wheel thing. The first time I played, I was really struck by the power of the engine at that point.
Ep1: Repressing the core. I haven’t played through all of Ep1 in a while, but I consistently play through that section.
Ep2: The chamber in which the extraction of the larval essence took place.
My favourite moment of all the Half-Life series, is without a doubt, the section in HL2 where you cross the underside of that bridge, best architecture I’ve ever seen in a game!
Fry the testacles???