Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
AOE II is a great old school game. Now that I have AOE III, I only occasionally play AOE II, but when I do, I'm hooked on it for a week.
AOE II has great graphics, great plots, and a really good range of possible units and civilizations. You can play as everybody from the Saracens to the Celts. They have Cataphracts and Woad Raiders. Trebuchets to battering rams, and champion swordsmen to paladins.
Great game, I recommend it.