The Advance Wars series is full of excellent, catchy music. Given how you'll be listening to a character's music everytime it's their turn, it's a good thing, too.
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Advance Wars/Black Hole Rising/Dual Strike
Since the themes are done in a variety of styles, there's a good chance that one of the themes will be somebody's favorites. Especially for the first three Advance Wars games. So let's list 'em all!
Orange Star:
Andy's Anthem Surprisingly, Andy is the only one with an "anthem" instead of a theme.
Von Bolt's Theme. Absolutely overblown and pompous, with the use of bagpipes to reinforce his evilness. Very fitting for a Big Bad.
But it's not just the themes that get attention in this game...
Black Hole Coming, from the first and second games. Despite being from the lighter incarnations of the series, is incredibly dark and foreboding. A fitting tune to hear when preparing for the last few levels in the game. You know you're playing by Black Hole's rules, and failure is not an option.
The Black Hole Rising ending music makes you think about all the memories you'll have from campaign, and all those virtual lives lost in freeing Macro Land from Black Hole's tyranny.
The Green Earth Theme really carries the sense of a long and drawn out conflict, making everyone weary, yet the battle is far from over.
"It's a Trap!" from Duel Strike. Black Hole mocks you and your attempts to stop it.
Days Of Ruin/Dark Conflict
Days of Ruin had a darker and grimmer setting, and its set of COs tended to add bombastic rock and roll to the more traditional techno beats. "Hope Never Dies", Brenner's theme, is merely the beginning. The theme fits it's name perfectly though. Getting your ass handed to you on a gold plate, sometimes you don't want to go on. Then your opponent end his turn and Brenner gets on stage, instantly pumping liquid courage into your ears.
Flight Of The Coward, Waylon's theme, is also worthy of mention. Particulary worth mentioning concerning his theme is that the first time you encounter him he is fleeing and you only hear the comical intro of the song and then it cuts to the next player because his turns are so short. He seems like a joke. The first time you face him in battle though you get past the intro and know that he is serious now.
Decadence, a piece from the game that was used in the trailers.
Power Up. It drives home the "never give up hope" attitude with all the force and fury of a typhoon and appropriately boots up for the first time as you're (hopefully) making a come back against Admiral Greyfield. Also, it's dark counterpart Stormy Times is no slouch in reminding you that all hope is lost for your cause.
The Big Bad's themes in every Advance Wars game so far have been memorable, and Puppet Master, Caulder's theme, is no different. With heavy drum beats and a demented circus-like theme, it really fits the mad scientist you're trying to face off with.