It's so hard to choose a favorite from all the quotes in the Half Life series, but one of the very best one I know would be a quote at the end of Half Life 2, where the G-Man told Gordon Freeman:

"Rather than offer you the illusion of free choice, I will take the liberty of choosing for you … if and when your time comes round again."
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence