Based on the game by Valkyria.
What is a great action-packed anime?
Obviously you've heard of the big ones like DBZ, Naruto, bleach, fairy tail, inuyasha, one piece.
Them aside if you like Mecha you will enjoy Gundam animes.
Watch Gundam seed or Gundam 00 and if you like them you can check out Gundam wing and many other countless titles in this franchise. If you like martial arts: Rurouni Kenshin, Baki the grappler (a bit cheesy but the fights are brilliant), Hajime no ippo, And of course code Geass, my favourite which mixes action, Mecha, sci-fi, fantasy, thriller into a unique thing.
I wish they made a 500 episode code Geass..well nah that might've ruined it.