This will be a re-watch for me, but it has been a few years, so while I still remember the broad strokes I have hopefully forgotten the smaller twists, and if I haven't we will find out how well it does foreshadowing.
Expect to get hooked right from the first episode, then start to wonder where it is going in the late-middle episodes, and then get blown away by the sheer epic scale of the conclusion.
Our main character is named Lelouch, which rhymes with "the douche" and is a pretty silly name. They start off playing the normal school boy card, but drop that facade pretty damn quick as he is given magic powers and an army of mechs to join in on the world-spanning conflict. Also, all the other key players in this world-spanning conflict just so happen to go to his school, a fairly preposterous trope played up to the fullest.
Said world-spanning conflict is between the Empire of Brittania (there is a weird backstory that since the ancient Romans never invaded Britain in this history the empire of Brittania was able to conquer the entire world two thousand years later, which shows a comical lack of understanding of British history, but oh well) and the freedom fighters of District 11 (the Isle of Japan). The conflict makes very little sense and I recall it seeming like a fairly generic conflict with the details being largely unimportant, even though the show goes out of its way to provide some quality expository world-building.
I don't remember the music being exceptional, though I do still have one of the OPs (Colors by Flow) on my MP3 player:
Finally, I could not find this anywhere, but I found a copy on youtube from the legitimate sounding AnimeHD Anime. First episode is here, but if anyone thinks for a second that this is not legit, let me know right away and I will pull down the link and keep searching for a source that will support the artists.
EDIT: Ok, just watched the first episode. Honestly I was kind of expecting that my hazy recollection of this show was inflated. When doing this writeup, I rather though to myself that it was more or less a given that this was the show that would drop out of the top five.
But holy shit that first episode. A marvel of pacing, and having seen the show before it sets the plot all the way to episode 50 if you know what to look for. The ambient music was better than I remembered, and while this is not a show possesed of a single ounce of subtlety, the frenetic pace and vibrant characterizations probably wouldn't hold up in anything but a cartoon universe.
A side note, I had assumed that Lelouch got purple eyes when he was hit by the Geass, but he clearly has purple eyes whenever he is being particularly clever or dastardly, and they revert all the way to brown when he is acting in a pedestrian manner. Of course, when he goes full Geass, his eye gets even stranger.