Dagger
The Unfinished Business are the Golden levels for TR1. You can download and run them, as long as you have the original game.
The Lost Artifact is a stand-alone game, but it's considered as the Gold edition of TR3. It's not like the TR1 and TR2 Gold levels, because as I said it's a stand-alone game, which means that you can play it without having TR3. You cannot download The Lost Artifact. You can buy it from a store close to you or an online store like amazon