Star Wars Empire at War is a strategy game.
Unlike some strategies, Empire at War is very basic. With little micro management, and a small unit cap. This makes it great for those new to the genre, who are looking to get into it.
The gameplay is in real-time. Meaning it is actually fun, unlike turn-based titles. There are two types of battles: space, and land.
In space battles you have a space station, which you can upgrade. Through this station, you build new units and buy upgrades for them, unlocking more units and upgrades as you upgrade the station. You must destroy the enemy's station to win.
The land battles put you on a planet in the Star Wars universe. You have a base with multiple buildings, each one allowing you to buy different units/upgrades. As with the space station, you can upgrade your central command building to unlock more advanced technology. You must destroy the enemy's base to win.
With both battle types, you can change the win conditions. So instead of just having to destroy their base, you have to wipe them out completely, etc.
The Gold Pack comes with both the original Empire at War, and the Forces of Corruption expansion pack. Unfortunately Forces of Corruption has some balance issues, but the game is still extremely fun.
The original game allows you to play as either the Empire or the Rebellion. It has it's own campaign, which is around 5 hours or so in length. But as with most strategy games, the campaign is more of a slow tutorial to prepare you for multiplayer.
Forces of Corruption adds a new campaign, and also allows you to play as the Consortium. Which adds new units, upgrades, abilities, and requires you to change your strategy in certain ways.
The multiplayer still has a very active, but very small, community. If you do plan to get the game, be sure to switch your location to the US in the options, otherwise you will see few, if any, matches.
Empire at War is an excellent RTS, and definitely one to consider getting whether you are a veteran of the genre, or have never played one before.