This expansion to Age of Empires II: The Age of Kings is one that you can't go without. You'd be missing great content.

User Rating: 8.5 | Age of Empires II: The Conquerors Expansion PC
Expansions usually feel like cheap add-ons just to suck people for more money since they usually cost about two-thirds the price of the required game. But The Conquerors expansion cleans the game with some very fresh updates and new races and units. I can't play a multiplayer Age of Empires II game without having all the content in it.

Look at this the way you would at the Brood War expansion of Starcraft. There's really not very much core gameplay added, just some memorable single player campaigns and additional content. But the content is very necessary and *cool*.

The gameplay is more rounded out and made more interesting with the addition of the Native American civilizations of the dark age times, along with the the conquistadors or *conquerors*, the Spanish.

If you get The Age of Kings, don't go without The Conquerors. (And check out my review of The Age of Kings)