[Isaac]

"Haven't you understood by now that I don't speak your fucking language?" - Max Payne 3

"There's still light at the end of the tunnel", "there's no light if It's not a tunnel. It's a hole" - Max Payne 3 (A short dialouge between Passos and Max)

"Let me guess, three alarms and the mission's over?" "Of course not, this is no video game Fisher" - Tom Clancy's Splinter Cell Cayos Theory (A convo between Lambert and Sam in the start of the third mission of the game)

These may not be the best quotes from any game, but they're all I can think of on a short notice.

[A Good Username]

"The Enrichment Center is required to remind you that the Weighted Companion Cube cannot talk.

In the event that it does talk, The Enrichment Centre asks you to ignore its advice."

[DestructoSphere]

The cake is a lie - Portal

[aluthrenite]

"I never asked for this." - Adam Jensen

[evin7]

Ay karumbaa! from Spec Ops 2002 on ps1