1. It has the best set-piece moments ever
No game choreographs its tension and mayhem as well as this. Whether it's a nervous train-ride into the depths of the desert that ratchets up the fear factor, or an all-out gun battle involving hundreds of soldiers and giant ants in a run-down prison, Half-Life games are peerless in the way they set up memorable scenes that will leave you reaching for a stiff drink.
