Starcraft: Broodwar is a sequel to the awesome original game, "Starcraft".
The single player (not campaign mode) is for you to test the skills you earned during the campaign to work. You can experiment on which strategies are best here. You may even test out maps you made in this mode. The Starcraft: Broodwar AI is designed to respond to how the map is made. If you make a map that has too much money, AI will be easy. This is just an example. Blizzard has put in tons of new multiplayer maps and the original map "Big Game Hunters" is back. This map was known for its brutal and persistent computer AI which most Battle.net players practiced on.
Veterans of the original Starcraft will remember the good campaign editor. Here, you can build your own maps or even create your own missions! This is well done and is easy to use. Almost anything you want to create can be made with this program which comes with the expansion as well as the original.
Brood War gives you the basic three teams to pick. The three races each have their own strong and weak points. For example, terran firebats can burn the fleshy zerg easily with their high tech units. Terran should be used only for experts since their units can't take too many hits and require a lot of microing (doing a lot at once). Protoss is in the middle. They're units are built to take hits, but are expensive. The money is worth it since they have the strongest units in the game. Zerg is recommended for newbies. They have cheap units which you can build in large bulk. Swarm your enemies if you want, as they are good at rushing enemies. Your units are weak, but pack a punch when sticking together and used the right way. Take this into consideration as most of your time will be spent on the multiplayer. Battle.net is free and you can go against anyone from friends to even strangers to test your skills.
Overall, this game will keep you glued in until another real time strategy game developed by Blizzard is out. Its outstanding new units and necessity for strategy keeps you coming back for more Starcraft.