Alien is a card Type in GBM SCG. It is a medium-larger sized Type and is one of the main card types of the game, but its numbers are considerably lower than the other main Types. The Alien cards are generally made up of extra-terristial themed-creatures and space/sci-fi themed Monster and Ability cards.
The Alien Type is unique as it is much more aggressive than other types.
While weaker monsters like Alien King and Bonza's are used for defensive purposes, even the Bonza cards have powerful tactics designed to quickly take a large number of the opponent's HP.
The Alien Swordmaster, Alien Warrior and Enranged Alien Warrior monsters are the most aggressive of the Type. These 3 monsters have strong Ability cards and methods for quickly gaining high attack and wiping the opponent's field clean.
The Alien Type is very good for over-aggressive and fast-thinking tactics, but an Alien-deck is generally useless and ineffective against Stall Decks and Fusion Decks, putting it at the disadvantage.