"Here come the test results: 'You are a horrible person'. That's what it says, 'a horrible person'. We weren't even testing for that!"

Anything Glados from Portal 1/2--still one of very, very few games to actually make me laugh. But also the Cave Johnson "when life gives you lemons" rant comes to mind, because it's both funny and poignant.

"Well, This is the part where he kills us."

"Hello. This is the part where I kill you."

CHAPTER 9: THE PART WHERE HE KILLS YOU

Achievement Unlocked: The part where he kills you

"The right person in the wrong place can make all the difference in the world" - Half Life 2

The creepy gait of his voice gives me goosebumps every time.

Had to be me. Someone else might have gotten it wrong.

You must construct additional pylons.

Words to live by.

Wololo.

War... war never changes.

All your base are belong to us.

Lots of good bioshock quotes, but the standout:

We all make choices, but in the end our choices make us

I’m here to kick ass and chew bubblegum. I know it’s from a carpenter film, but I heard it first in Duke Nukem.

This was a triumph
I'm making a note here, "Huge success"
It's hard to overstate my satisfaction
Aperture Science
We do what we must because we can
For the good of all of us, except the ones who are dead

All your base are belong to us.

You forget a thousand things every day, make sure this is one of them.

Michael, GTA V

Truth is, the game was rigged from the start. -Benny

Alternatively:

Hope this interaction does not lead to any fallout between us. Fallout: New Vegas. -Benny

It's a-me, Mario!

From Assassin's Creed 2. Might be known from some other game too, I dunno.

I bought FC3 without knowing what the game was because of this monologue:

Vaas: "Did I ever tell you what the definition of insanity is?

Insanity is doing the exact same fucking thing, over and over again expecting shit to change. That. Is. Crazy.

The first time somebody told me that, I dunno, I thought they were bullshitting me, so, boom, I shot him. The thing is, he was right

And then I started seeing, everywhere I looked, everywhere I looked all these fucking pricks. Everywhere I looked, doing the exact same fucking thing... over and over and over and over again thinking: 'This time is gonna be different.' No, no, no please... 'This time is gonna be different.'

I'm sorry, I don't like... The way... you are looking at me,. Okay!? Do you have a fucking problem in your head, do you think I am bullshitting you, do you think I am lying? Fuck you! Okay? Fuck you!

It's okay, man. I'm gonna chill, hermano. I'm gonna chill -

The thing is... Alright, the thing is I killed you once already. And it's not like I am fucking crazy. It's okay... It's like water under the bridge

Did I ever tell you the definition... of insanity?

What is a man? A miserable little pile of secrets.

Had to be me, someone else might've gotten it wrong.

0.000% of Communism has been built. Evil child-murdering billionaires still rule the world with a shit-eating grin. All he has managed to do is make himself sad. He is starting to suspect Kras Mazov fucked him over personally with his socio-economic theory. It has, however, made him into a very, very smart boy with something like a university degree in Truth. Instead of building Communism, he now builds a precise model of this grotesque, duplicitous world.

"Dear humanity: We regret being alien bastards. We regret coming to Earth. And we most definitely regret that the Corps just blew up our raggedy-ass fleet!" - Avery Johnson

"(while looking into the mirror) Despite everything, it's still you.", from Undertale.

Also a bunch of lines from the Happy Happy cult members in Earthbound.

Ah shit here we go again.

"You're on a path in the woods."

"The thing about happiness is that you only know you had it when it's gone. I mean, you may think to yourself that you're happy. But you don't really believe it. You focus on the petty bullshit, or the next job, or whatever. It's only looking back by comparison with what comes after that you really understand, that's what happiness felt like."

-Conrad Kellogg; Fallout 4.

"What kind of idiot are you?"

"I dunno. The good kind?"

Bulletstorm.

Not exactly words of profound wisdom, but still…

“You look like a cut of fuckable meat. Are you?”

Adam Smasher, Cyberpunk 2077

There’s also another great quote from Discworld, where the conversation starts with “expect the unexpected”, but eventually concludes with “expect the expected”. Lots of funny philosophical arguing back and forth.

LEROY JENKINS!

"I'm here to kick ass and chew bubblegum, and I'm all outta gum" from Duke Nukem (originally from the movie "They Live").

The truth, Walker, is that you're here because you wanted to feel like something you're not: a hero.

"When fate closes a door, luck opens a window, and karma de-activates the alarm system!"

• Sam, in Poker Night at the Inventory 2

Edit: wrong character lol

Go hang a salami, I'm a palindrome

A man chooses, and slave obeys.

Protocol 3: Protect the Pilot

One of the best campaigns I have ever played and definetly my favourite shooter.