Eight years ago Blizzard released the Brood War expansion pack for Starcraft and people are still logging on to battle.net to play it. The expansion pack added only a few units for each side, but these minor additions led to huge gameplay changes. Invisible units like Lurkers and Dark Templar forced players to beef up their defenses or get trashed by blurs on screen. Some classic strategies from the first game still worked like rushing in with your worker units, but you might want to watch these clips from some excellent Starcraft players to learn some new tricks.
Past the break is the opening video for Starcraft: Brood War.