I imitate gman's voice from the series "Half-Life" by reading off many of his lines in the game (though I don’t recite all of them perfectly). I apologize that the audio quality isn't fantastic as I recorded this as part of a video and was far from the microphone, Mr. Freeman.

Timestamps:

Half-Life 1 - 00:00

Half-Life 2 - 01:58

Half-Life 2: episode 1 – 04:07

Half-Life: Alyx - 06:20

Half-Life: Opposing - 07:42

Entropy Zero 2 - 09:26

Made it up – 11:15