I believe The Beatles: Rock Band came the closest to being perfect. Eveything about that game was just beautifully done and the only things missing was Pro Drums, an option for Keys, and a few more Beatle songs (Hey Jude, Strawberry Fields Forever, Yesterday etc. etc.)
The original Half Life is pretty fun, but I’d recommend checking out Black Mesa. It’s a remake of the original game in the same engine that Half-Life 2 uses, and changes some things for the better.